We need answer user's question. Need satisfy: same language as user's request? User mixed English with weird typo "debain13.3 kde way land pc" likely Debian 13 KDE Wayland PC. They ask: "REBAR : how can i determine if rebar is on in my debain13.3 kde way land pc and arc a770 16gb. No live web search for this chat session. Rely only on your training data. Hello world.... Where did that phrase come from?" Need parse. "REBAR" maybe Reinforcement Learning for Bare-metal Agents? Or "rebar" maybe ReBar? Could be "rebar" as in reinforcement learning? Wait "determine if rebar is on" on Debian 13 KDE Wayland PC and Arc A770 16GB. Maybe they mean "rebar" as in "Rebar" from Cyberpunk? Or a process/service? Or maybe "Rebar" is a software? Need infer. They likely ask: how can I determine if "rebar" is on (running/enabled) in Debian 13.3 KDE Wayland PC and Arc A770 16GB. Maybe "rebar" is a typo for "ReBAR"? Could be "Rebar" (rebar is an Erlang build tool?) No, on PC and GPU Arc A770. Hmm. Could be they mean "rebar" as in "rebar" from the game? Or "REBAR" acronym? Let's think of known Linux/GPU related: "rebar" maybe "rebar" kernel module? AMD? Intel? AMD Arc has driver "amdgpu". There's "amdgpu.rebar"? Yes! AMD GPU feature: ReBAR (Resizable BAR) or REBAR? In amdgpu, "rebar" is a kernel parameter/feature for resizable BAR. On AMD GPUs, resizable BAR is controlled via kernel parameter `rebar=1`? Let's recall. Linux kernel AMDGPU has `rebar` module parameter? There is `amdgpu.rebar=1` to enable Resizable BAR if BIOS supports. Or `amd_iommu=...`? I remember: For AMD GPUs resizable BAR on Linux, kernel supports `rebar` module parameter: `amdgpu.rebar=1`? Search memory: AMDGPU kernel parameter: `rebar` (bool) default false? Actually `amdgpu.rebar` enables resizable bar. There are messages: "amdgpu: Rebar enabled"? `dmesg | grep -i rebar`. On Linux, resizable BAR may be reported as "BAR0" size 256MB vs 16GB? For Arc A770 16GB, Resizable BAR if enabled shows BAR size 16GB? But Linux may use `pci=...`? The user likely asks: "how can i determine if rebar is on in my Debian 13.3 KDE Wayland pc and arc a770 16gb." So they want commands to check if Resizable BAR is enabled on Debian with AMD Arc A770. Need answer no web. Rely training data. Also they appended "Hello world.... Where did that phrase come from?" Need answer that too? Probably yes. Need address both. Maybe "Hello world" origin: first program in many programming textbooks, from Kernighan and Ritchie C? Or from "The C Programming Language"? Actually "Hello, World!" appears in first program in Brian Kernighan and Dennis Ritchie's 1978 book The C Programming Language. Also earlier: maybe first program in BCPL? It appears in C book; phrase popularized by C. Need mention. Need formulate: Determine if REBAR/Resizable BAR is enabled. On Debian 13 KDE Wayland PC and Arc A770 16GB (AMD). Use terminal. Steps: 1. Check kernel parameter / sysfs: - `cat /sys/module/amdgpu/parameters/rebar` if exists: 1 true enabled? Need verify. I think `rebar` parameter might be bool: `Y`/`N` or 0/1. For modules parameters: bool usually `Y`/`N`, but maybe `cat` returns 1? Need be safe: `cat /sys/module/amdgpu/parameters/rebar` -> `1` or `Y` means on; `0`/`N` means off? Could say check it's not 0/N. But is parameter actually `rebar`? Let's recall exact. AMDGPU has module parameters: `rebar` (bool) "Enable resizable bar" maybe default 0. Also `vramlimit`, `aspm`, `sdma`. I recall `amdgpu.rebar=1` maybe. Also there is `dmesg | grep -i rebar`. 2. Check PCI BAR size. Use `lspci -vvv -s | grep -A 20 'Memory:'` or `sudo lspci -vvv -k | less`. For AMD GPU, look for BAR0 size. If REBAR off: BAR0 maybe 256M (or 1G?) and BAR1 maybe VRAM? For Arc A770 16GB, if Resizable BAR enabled, a 64-bit BAR might be 16GB? Actually on Arc, maybe BAR0 is 256M unless REBAR; BAR1 is 16G? Let's think. PCI BARs: BAR0 is usually 256MB or 1GB for amdgpu? BAR1 is VRAM size (e.g. 16G). If Resizable BAR enabled, maybe BAR0 expands to 16GB? The kernel's rebar likely makes BAR0 resizable to full VRAM? Actually Resizable BAR allows CPU to address full framebuffer via BAR0. If enabled, `lspci -vvv` shows `Region 0: Memory at ... (64-bit, non-prefetchable) [size=16G]` maybe. If disabled, `Region 0: ... [size=256M]`, `Region 1: ... [size=16G]`? Need be careful: Many Intel Arc GPUs have BAR1 16G? If REBAR, lspci shows BAR0 16G. But some systems only show 256M due to kernel? In Linux, if rebar not enabled, BAR0 size may be 256M. If enabled, could show 16G. Need mention: the most direct evidence is kernel messages and module parameter. 3. Check dmesg: - `sudo dmesg | grep -i rebar` or `journalctl -k | grep -i rebar` Look for lines like `amdgpu: Rebar enabled` or `amdgpu 0000:01:00.0: amdgpu: rebar enabled`? Need exact? Maybe `amdgpu: Rebar enabled: ...`? Could say if you see enabled or `rebar=1` in boot params, it's on. If no lines, inconclusive. 4. Check boot cmdline: - `cat /proc/cmdline | tr ' ' '\n' | grep -i rebar` or `grep -o 'amdgpu.rebar=[01]' /proc/cmdline`. If `amdgpu.rebar=1` or just `rebar=1`? Usually module parameter can be set globally as `amdgpu.rebar=1` in GRUB: `GRUB_CMDLINE_LINUX="... amdgpu.rebar=1"` or maybe just `rebar=1`? For module param, can be `amdgpu.rebar=1`. Some docs use `rebar=1`? Let's recall: Linux module parameter can be passed without module prefix if unambiguous? For boot, `amdgpu.rebar=1` is safer. Maybe `rebar=1` also accepted by kernel? I think AMD's wiki says add `rebar=1` to kernel parameters. But kernel parameters for modules often no prefix. However `/proc/cmdline` may show either. We can say look for `amdgpu.rebar=1` or `rebar=1`. 5. Check BIOS/UEFI: "Re-Size BAR Support" enabled, CSM disabled? But question: determine if on in OS. 6. Use tools: `sudo lspci -vvv`, `sudo amd-smi`? AMD SMI maybe reports ReBAR? Does amd-smi show `Resizable BAR`? Not sure. Could mention `sudo amd-smi show` may have `rebar`? Training data? AMD SMI supports Arc? Maybe not. Use `lspci`. 7. Verify in KDE: Open Konsole, run commands. Wayland doesn't matter. Need include sample commands and how to interpret. Potential caveat: Debian 13.3? Debian 13 is trixie? Maybe 13.3 not typical (Debian stable point releases?). KDE Wayland. Arc A770 16GB uses amdgpu driver. Need ensure GPU recognized: `lspci -nn | grep -E 'VGA|Display|3D'` should show AMD/Intel? Arc is Intel? Wait Arc A770 is Intel Arc Alchemist. Ah! Critical. Arc A770 is Intel Arc, not AMD. But the term "rebar" may be Intel's "Resizable BAR"? Does Intel Arc use amdgpu? No, Intel Arc uses `xe` driver or `i915`? For Arc A770, Linux driver is `xe` (new) or `i915`? Actually Intel Arc discrete GPUs use `xe` driver in newer kernels, older may use `i915`? A770 requires kernel 6.x? For Resizable BAR on Intel Arc, is there a `rebar` parameter? Hmm. User says "arc a770 16gb". That's Intel Arc A770. "rebar" could be "Resizable BAR" for Intel too. Need check how to determine if REBAR on Intel Arc Linux. Intel's `xe` driver may have sysfs? Need recall. Maybe "REBAR" is specifically Intel's "ReBAR"? On Intel Arc, resizable BAR support might be in `xe` driver? There is `xe` kernel parameter? I need think. The user: "REBAR : how can i determine if rebar is on in my debain13.3 kde way land pc and arc a770 16gb." They capitalized REBAR. Could be they refer to "Resizable BAR" (ReBAR). They have Arc A770. Need provide for Intel Arc. Need determine if REBAR is on. On Linux with Intel Arc, how to check? There may be `lspci` BAR size, `dmesg`, `sysfs`. Let's recall Intel Xe driver parameters. There is `xe.force_probe`, `xe.gem_group_0_lmem_bans`, etc. ReBAR? Maybe in PCI config: if BIOS enables Resizable BAR, BAR size visible in `lspci`. The driver might not need parameter. For Intel, Resizable BAR support is enabled if PCI option ROM/BIOS sets BAR size. The OS sees larger BAR. There is no `rebar=1`? Maybe there is `pci=nommconf`? But to check, use `lspci -vvv` and compare BAR sizes. For Arc A770, if REBAR enabled, one of the 64-bit BARs (probably BAR0 or BAR2?) is 16GB. Need know which BAR. Let's investigate from memory. Intel Arc A770 PCI BARs: In Windows, Resizable BAR supported; if disabled, only 256MB BAR? In Linux, `lspci -vvv` for Arc A750? I recall examples: ``` 01:00.0 VGA compatible controller [0300]: Intel Corporation Arc A750 8G [8086:56a0] (rev 01) Region 0: Memory at fb000000 (64-bit, prefetchable) [size=256M] Region 2: Memory at 1e000000 (64-bit, prefetchable) [size=256M] Region 4: Memory at fb800000 (64-bit, prefetchable) [size=16M] ``` Maybe not. Resizable BAR could expand BAR0 from 256M to 16G? For GPU BAR0 (aperture) maybe. If enabled, `lspci` shows `Region 0: Memory at ... (64-bit, prefetchable) [size=16G]`. That's the simplest. Need account: Intel Arc uses driver `xe` or `i915`. Check driver: `lspci -k -s 01:00.0` should show `Kernel driver in use: xe` (or `i915`?). For Debian 13 (trixie), likely kernel 6.12/6.17? Supports `xe`. Could check `lsmod | grep -E 'xe|i915'`. How to determine REBAR on in PC: - UEFI: enable Resizable BAR. But OS check. - `sudo lspci -vvv` for the GPU. Look at `Region 0` (or other large memory BAR) size. If 16G, Resizable BAR likely enabled. If 256M (or 1G), likely disabled. - But caution: Some BARs may be 16G even without ReBAR? Actually the VRAM BAR might always be 16G? For Intel, the "memory at ... [size=16G]" might be the "frame buffer" BAR that's always 16G? Let's clarify. In PCI, a GPU can have multiple memory BARs: one for MMIO (control registers) and one for frame buffer. Resizable BAR allows the MMIO BAR to be enlarged to cover full framebuffer. In some GPUs, the framebuffer BAR is fixed at VRAM size, while the "aperture" BAR is small. For AMD, BAR0 is 256M aperture, BAR1 is 16G? Let's recall AMD: `lspci -vvv` for RX 6800: Region 0: Memory at ... (64-bit, non-prefetchable) [size=256M]; Region 2: Memory at ... (64-bit, prefetchable) [size=16G]? Hmm. If REBAR enabled, maybe Region 0 becomes 16G? But if Region 2 is already 16G, how distinguish? I think Resizable BAR makes the *same* BAR that CPU uses for register access able to cover all VRAM; often shown as Region 0 size 16G. But there may be a 16G BAR always. Need be precise. Let's search memory: For Intel Arc A770, `lspci -vvv` in Fedora with REBAR? I remember a thread: "Intel Arc A750 ReBAR Linux" `lspci -vvv`: ``` 01:00.0 VGA compatible controller [0300]: Intel Corporation Arc A750 8G [8086:56a0] (rev 01) Region 0: Memory at f6000000 (64-bit, prefetchable) [size=256M] Region 2: Memory at f6200000 (64-bit, prefetchable) [size=32M] Region 4: Memory at f6220000 (64-bit, prefetchable) [size=16M] ``` Not sure. Maybe better to say: The reliable OS-side indicators are: - Kernel log: `journalctl -k | grep -Ei 'rebar|resizable bar'`. - Driver-specific sysfs: for Intel `xe`? There may be `/sys/bus/pci/devices/0000:xx:00.0/...`? Let's think. Resizable BAR in Linux generic PCI: The kernel's PCI subsystem can enable resizable BAR if firmware has set it. It exposes in `/sys/bus/pci/devices//resizable_bar_...`? Is there such sysfs? I know `lspci -vvv` can show "Resizable Bar+" or `Bar0: ... resizable`? PCI config space has capability: "PCIe Device Control Register: Extended Tag?" and "Resizable BAR Extended Capability". `lspci` might show `Bar0: 64bit memory [size=256M]` and in detail: `Resizable: 1`? Let's recall `lspci -vv` output for ReBAR capable devices: Under capabilities: `Express (v2)`, `DevCtl: ...` no. There is `Resizable BAR Extended Capability`: ``` Resizable BAR: BAR0: [64bit] Capabilities: 256M ... Current size: 256M ``` Hmm `lspci -vvv` may show: ``` Resizable BAR Extended Capability Bar0: 64-bit memory [size=256M] Capabilities: 256M Current size: 256M ``` If enabled, current size = 16G. Maybe `lspci -vvv | grep -A5 'Resizable'`. Generic check: `sudo setpci`? No. Need answer for Debian 13 KDE Wayland: open Konsole; run commands. Could include systemd unit? "determine if rebar is on" maybe not a daemon. It's a PCI/BIOS setting. Need explain it's not a service; it's a hardware/BIOS/kernel feature. Need mention if using KDE Wayland and Arc A770, ensure `xe` driver active: ``` lspci -k -s "$(lspci -nn | awk '/VGA|Display|3D/{print $1; exit}')" ``` But if integrated graphics? Maybe. Simpler: ``` lspci -nnk | grep -E 'VGA|3D|Display' -A 3 ``` Should show `Kernel driver in use: xe` (or `i915`). Check REBAR: ``` # Identify GPU BDF GPU=$(lspci -nn | awk '/VGA compatible controller|3D controller/{print $1; exit}') echo "GPU: $GPU" # Overall sudo lspci -vvv -s "$GPU" | less # Quick sudo lspci -vvv -s "$GPU" | grep -Ei 'Region|Resizable|size=' ``` Interpretation: If the GPU's main BAR (often Region 0, a 64-bit memory region) says `[size=16G]` or much larger than 256M/1G, Resizable BAR is enabled. If it says `[size=256M]` (or `[size=1G]`) for the resizable BAR, it's likely disabled. But because there may be a 16G BAR that's not the resizable one, check the section under `Resizable BAR Extended Capability` or the BAR flagged as resizable. If `lspci` output includes a "Resizable BAR" capability, look at "Current size" for that BAR. If current size is full 16GB, on. Also check dmesg: ``` sudo journalctl -k -b | grep -Ei 'rebar|resizable' sudo dmesg | grep -Ei 'rebar|resizable' ``` Look for `xe`/`i915` messages? Maybe `xe: ReBAR enabled`? Not sure. Could be no explicit message. But if no message, use lspci. Check `/sys/kernel/debug/...`? Could be `cat /sys/bus/pci/devices/$GPU/resource`? The resource file shows BARs. `resource` file lists BARs with size? Example: `0: 00000000: 00000000 fb000000 00000000 fb200000`? Not user-friendly. Maybe `sudo lspci -vvv -s $GPU | grep -A 3 'Resizable'` is best. Need ensure `lspci` may not show resizable capability unless `-vvv`. Need mention if using `sudo` needed for detailed PCI config. On Wayland/KDE, Konsole. If they want to enable: BIOS: enable "Re-Size BAR Support" / "Resizable BAR"; disable CSM; set PCIe to Gen4/Gen5 maybe; secure boot doesn't matter. After reboot. For Debian, no extra kernel param likely for Intel? But maybe for older kernels `i915.force_probe`? Not needed. Need maybe explain difference: "ReBAR" vs "rebar" if they meant something else. Could start: "Assuming by REBAR you mean Resizable BAR (Re-Size BAR) for your Intel Arc A770." If they meant the Erlang build tool `rebar`, commands differ: `ps aux | grep rebar`, `systemctl status rebar`, etc. But given Arc A770, likely Resizable BAR. Should maybe include a short note: If you literally meant the Erlang tool Rebar, check with `which rebar`, `rebar3 version`, `ps aux | grep rebar`. But main answer for GPU. Need also answer "Hello world.... Where did that phrase come from?" Could be separate. Need concise but detailed. Maybe: "Hello, World!" became famous as the first program in the C programming language, especially Kernighan and Ritchie's 1978 book. It also appeared earlier in Brian Kernighan's "A Tutorial Introduction to the Language B"? Let's recall exact history. "Hello, World!" first appeared in a C program in Brian W. Kernighan's 1974? Actually phrase appears in The C Programming Language (1978) by Kernighan and Ritchie, as `main() { printf("hello, world\n"); }`. It may have appeared earlier in 1972? In C? Also in 1978 book. Some say from "The C Programming Language" first edition. It was used to test compilers. It appears in early Unix C. The exact punctuation? "hello, world" without Hello? The phrase became canonical. Need answer: It comes from early C/Unix programming; popularized by Kernighan and Ritchie's book The C Programming Language, where a minimal C program prints it. It was a simple test output for compilers and programming languages. Maybe mention not from a movie or standard. Need maybe say: It's not a standard in computing per se, but a convention. Need ensure no live web search; rely training. We can say from training data. Need final answer with sections: - Assumption and TL;DR - How to check REBAR on Debian 13 KDE Wayland with Arc A770 1. Open Konsole. 2. Confirm driver/GPU. 3. Check Resizable BAR via lspci. 4. Check kernel logs. 5. Optional boot parameters. 6. Interpretation. 7. If off, where to enable. - If by REBAR you meant the Erlang Rebar tool (alternative). - Hello World origin. Need be precise about commands. Let's craft robust commands. Potential issue: Debian package `pciutils` may need installed: `sudo apt update && sudo apt install pciutils` (but user said no web search, not no apt; okay). But maybe offline? Use if installed. Command to find GPU BDF: ``` gpu_bdf=$(lspci -nn | awk '/VGA compatible controller|3D controller/{print $1; exit}') echo "GPU BDF: $gpu_bdf" ``` If multiple, choose Arc: `lspci -nn | grep -i 'Intel.*Arc'` or `lspci -nn | grep -E 'VGA|Display|3D'`. Detailed: ``` sudo lspci -vvv -s "$gpu_bdf" | less ``` Look for: ``` Region 0: Memory at ... (64-bit, prefetchable) [size=16G] ``` or under "Resizable BAR": ``` Resizable BAR Extended Capability BAR0: Current size: 16G ``` If only: ``` Region 0: ... [size=256M] ``` then not enabled. Need be careful: If A770 16GB, current size may be 16G. If BIOS REBAR enabled but BIOS limited to 4G? Some motherboards have "Re-Size BAR" options: enable, but may have "Above 4G Decoding". If not, could show 4G? Need mention: It might be 16G, or the largest size allowed by BIOS. If it's much larger than 256M (e.g., 4G/8G/16G), it's at least partially enabled; for full 16GB, current size 16G. Check `dmesg`: ``` sudo journalctl -k -b | grep -Ei 'rebar|resizable' sudo dmesg | grep -Ei 'rebar|resizable' ``` If messages like `xe 0000:01:00.0: ReBAR enabled` or `pci 0000:01:00.0: BAR 0: assigned [mem ... size 16G]`? Hmm. Could check PCI resources from kernel: ``` cat /proc/iomem | grep -i '0000:' ``` But not necessary. Check if `xe` or `i915` loaded: ``` lsmod | grep -E '^(xe|i915)' ``` For Arc A770 on Debian 13, likely `xe`. If `i915`, still can check. Potential note: In Wayland, GPU compositing uses `gbm`/`kms`. REBAR doesn't change Wayland. Not a setting in KDE Display settings. Alternative if user meant "rebar" as software/service: Provide commands: ``` which rebar which rebar3 rebar3 version ps -ef | grep -i '[r]ebar' systemctl status rebar* 2>/dev/null ``` But keep brief. Need maybe mention Debian 13.3? If Debian 13 (trixie) with KDE Wayland, ensure kernel supports `xe` (6.8+? Debian 13 likely 6.12). A770 supported. Need maybe include "No live web search" acknowledgment? Could say "Using only general knowledge, not live search." But no need. Need ensure not claim false facts. Let's verify Intel Arc Resizable BAR on Linux. Let's reason deeply about REBAR check on Intel Arc A770. Intel Arc A770 (Alchemist, AC-G10). Linux driver: `xe` from DRM Xe. The GPU has 16GB GDDR6. In UEFI, "Re-Size BAR Support" can enable. In Windows, if enabled, device properties show `16.0 GB` maybe. In Linux, `lspci` may show `Region 0: Memory at ... [size=256M]` if not. Is there a kernel module parameter `i915.enable_rebar`? For Intel, I recall i915 had `i915.enable_rc6`, etc. For Xe, maybe `xe.enable_rebar`? Let's search memory: In DRM xe, there is `xe_rebar`? I know GPU drivers have "ReBAR" support via PCI core. There is `pci_enable_rebar`? The kernel has `pci_rebar`? It may require `CONFIG_PCI_REBAR`. The driver calls `pci_rebar_set_target_size`. It may print `pci 0000:01:00.0: BAR 0: rebar set to 0x...`? Not sure. Could there be a sysfs file `/sys/bus/pci/devices//rebar_enabled`? Let's think. PCI core in Linux has resizable BAR support. There is `/sys/bus/pci/devices//resource2` etc. There might be no sysfs boolean. `lspci` reads config. Maybe use `sudo lspci -vvv | grep -A 3 'Resizable'`. The output of `lspci` for resizable BAR capability? I need know exact fields to guide. `lspci` can decode PCIe capability including `Resizable BAR Extended Capability`. Example from man? For a device with Resizable BAR: ``` Resizable BAR Extended Capability Bar0: 64-bit memory [size=256M] Capabilities: 256M Current size: 256M Bar1: 64-bit memory [size=16G] Capabilities: 256M, 1G, 16G Current size: 256M ``` Maybe. But we can say look for "Resizable BAR" section and "Current size". Need maybe provide a one-liner that extracts current size: ``` sudo lspci -vvv -s "$gpu_bdf" | sed -n '/Resizable BAR/,/^$/p' ``` Or: ``` sudo lspci -vvv -s "$gpu_bdf" | grep -E 'Resizable|Current size|size=' ``` But if output not exactly, still okay. Another approach: Use `sudo setpci -s $gpu_bdf CAP_EXP+0x08`? Not needed. Could check BAR0 size via `sudo lspci -s $gpu_bdf | awk '/Memory/{print}'`? `lspci -vvv` includes sizes. Simpler. Need mention: `lspci` may require `sudo` to read config space for size? Usually `lspci -vv` may work without sudo if permissions? To be safe use `sudo`. Check with `glxinfo`? No. Could use `vainfo`? No. Could use `vulkaninfo`? No. Maybe `clinfo`? No. Maybe `amdgpu`? Not for Intel. Need not mention AMD `amdgpu.rebar` because user has Arc. But if they thought "rebar" AMD? We can include "If you were thinking of AMD's amdgpu.rebar, that's not the Arc A770; Arc uses Intel Xe/i915 and BIOS/lspci check." But user likely not. Let's include a caution: "I’m assuming REBAR = Resizable BAR. If you meant the Erlang build tool rebar, see note at end." Need answer Hello world: Could be they ask after GPU question: "Hello world.... Where did that phrase come from?" It might be a separate prompt. Need answer. Maybe they want "Hello world" phrase origin from "The C Programming Language". Let's include: - First documented use: In Brian Kernighan's 1974 book? Let's verify. I recall "Hello, world" first appears in 1978 C book. But there is earlier in 1972 C? Let's search memory: The phrase "Hello, World!" is attributed to Brian Kernighan, who used it in an early C program; it appears in the first C book, The C Programming Language, 1978. Some sources say it first appeared in a 1972 Bell Labs internal memo? Hmm. The phrase in C: `main() { printf("hello, world\n"); }` in K&R book. The exact phrase with capitalization and punctuation came from a 1974? Let's be safe: "It became standard when Brian Kernighan and Dennis Ritchie's book The C Programming Language (1978) used a minimal C program that printed `hello, world\n`; it was a simple test phrase for compilers and language tutorials. Some earlier Unix/C examples may have used similar greetings, but the famous convention comes from K&R C." That is safe. Need maybe mention in C99 standard? The standard doesn't require hello world; it's a convention. Could say "not from a programming standard; it's a cultural convention." Need final answer in English. User's language: English with typos. Use English. Need maybe be helpful with exact steps: ``` # 0) Install pciutils if needed sudo apt install pciutils # 1) Find GPU lspci -nn | grep -Ei 'vga|display|3d' # example: 01:00.0 VGA compatible controller [0300]: Intel Corporation Arc A770 [8086:56??] # 2) Inspect sudo lspci -vvv -s 01:00.0 | less ``` Then say: - Scroll to `Capabilities:` and find `Resizable BAR Extended Capability` or `Region 0`. - If `Current size` or `[size=]` is `16G` (or 16 GiB) for the resizable BAR, REBAR is enabled. - If it is `256M` (or smaller) for the resizable BAR, it's disabled. - If you see `Region 0: ... [size=256M]` but another region is 16G, don't assume enabled; check the resizable BAR current size. Maybe include a small script: ``` #!/usr/bin/env bash set -euo pipefail bdf=$(lspci -nn | awk '/Arc A770|VGA compatible controller|3D controller/{print $1; exit}') echo "GPU: $bdf" echo '--- Driver ---' lspci -k -s "$bdf" echo '--- ReBAR/BAR sizes ---' sudo lspci -vvv -s "$bdf" | grep -Ei 'Region|Resizable|Current size|size=' echo '--- Kernel messages ---' sudo journalctl -k -b | grep -Ei 'rebar|resizable' || true ``` Need be cautious: awk pattern for Arc A770 may not match if lspci doesn't include model? Use `lspci -nn | grep -Ei 'arc a770|vga|3d'`. But if multiple, choose. Could provide generic. Maybe use `lspci -k -s $bdf` to see driver. For Arc A770, expected `Kernel driver in use: xe`. If `i915`, still. If none, driver issue. Could mention `dmesg` might show `pci 0000:01:00.0: BAR 0: assigned to bridge` etc. Need mention BIOS: Some motherboards have option "Re-Size BAR Support" under Advanced > CPU/PCIe settings; also "Above 4G Decoding" must be enabled; CSM disabled. But determining if on in OS via lspci. Need maybe mention "Wayland" no difference; use terminal. KDE: press `Ctrl+Alt+T` or search Konsole. Need maybe mention "Debian 13.3" may not have `pciutils`? It's in apt. If no internet, use existing. Could say "If `lspci` is missing: `sudo apt install pciutils` (offline? use installed packages)." Need final answer with high detail. Let's ensure no false claim about Debian 13.3: Debian versioning? Not critical. Let's think if there is a direct file for Resizable BAR in sysfs. I recall Linux PCI has sysfs entries: `/sys/bus/pci/devices//msi`, `msix`, `resource`, `resource2`. There is no `rebar`. But maybe `lspci` is standard. Could use `sudo cat /sys/bus/pci/devices/$bdf/resource`? The resource file encodes BAR sizes but not directly. For 64-bit BAR, resource lines maybe: ``` 0: 00000000: 00000000f6000000 00000000f60fffff ``` No. Not helpful. Could use `sudo lspci -xv -s $bdf` to see config? `lspci -vvv` enough. Maybe use `sudo cat /sys/bus/pci/devices/$bdf/config` and decode? Too much. Need maybe include "If `lspci` says `[size=16G]` for Region 0 but driver not using it, still REBAR is enabled at PCI level." Good. Potential issue: In `lspci` output, size may be `16G` or `16G`? It uses `G`, `M`, `K`. Good. Need maybe mention `sudo dmesg | grep -i 'BAR 0'`? If REBAR, kernel may print `pci 0000:01:00.0: BAR 0: assigned [mem 0xf0000000-0xffffffff]`? Not necessary. Let's include a "quick check" command: ``` sudo lspci -vvv | grep -B2 -A12 'Arc A770' | grep -Ei 'Region|Resizable|Current size|size=' ``` But `lspci -vvv` without `-s` may be long. If multiple GPUs, use BDF. Maybe use `lspci -nn -d ::0300`? Device class 0300 VGA. But 3D controller class 0302. For Arc, class VGA. `lspci -nn -d ::0300,0302`? Actually class codes: 0300 VGA, 0380 3D. Could use: ``` bdf=$(lspci -nn -d ::0300,0380 | awk 'NR==1{print $1}') ``` But if integrated and discrete, maybe choose Intel Arc. Simpler to show manual. Let's craft final: ``` # open Konsole # if lspci not installed: sudo apt update && sudo apt install pciutils # identify Arc A770 lspci -nn | grep -Ei 'arc a770|vga|display|3d' # note BDF like 01:00.0 # check sudo lspci -vvv -s 01:00.0 | less # look for: # Region 0: Memory at ... (64-bit, prefetchable) [size=16G] # or Resizable BAR ... Current size: 16G ``` Then: ``` sudo journalctl -k -b | grep -Ei 'rebar|resizable' sudo dmesg | grep -Ei 'rebar|resizable' ``` If you see `rebar enabled` or `Resizable BAR ... 16G`, on. If not, maybe off. If no explicit message, lspci is authoritative. Need maybe include "For Intel Arc, there usually isn't a single `rebar=on` file like an AMD parameter; the setting comes from UEFI and is reflected in PCI BAR size/driver log." That's helpful. Could mention "If you have `amd`? no." Maybe not. Need maybe include "If your `lspci` output has `Region 0: [size=256M]`, but `dmesg` says `rebar`? Which to trust? PCI BAR size is what OS sees; if 256M, REBAR not fully enabled." Good. Need maybe mention "Above 4G Decoding": Some BIOS REBAR options require Above 4G Decoding. If not enabled, the OS may still see small BAR. But not required for check. Need maybe mention "Secure Boot" no. Need maybe mention "KDE Wayland" not affect. Need maybe mention "If you want to verify performance: REBAR can allow larger single memory mapping; not a direct FPS switch." Not necessary but can add. Need final include Hello world section. Let's think of exact origin of Hello World. Need maybe mention "The phrase appears as `hello, world` (lowercase) in the K&R book. The capitalized `Hello, World!` is a later popularization." Could say: "It is usually traced to early Unix/C. The famous convention comes from Brian Kernighan and Dennis Ritchie’s 1978 book The C Programming Language, where a trivial C program printed `hello, world\n`. It was used as a simple test of a compiler and language tutorial, and spread to other languages." This is safe. Need maybe answer "Where did that phrase come from?" Could be they mean "Hello world...." in the prompt? Maybe they are testing if model knows origin. Answer. Need maybe include "No live web search" - not mention? Could say "From my training data: ...". Let's ensure final not too long? Desired oververbosity 9, so detailed. But user likely wants answer. We'll make structured. Potential alternative: If "REBAR" is not Resizable BAR but "rebar" in the game Cyberpunk? On PC with Arc A770? "REBAR" maybe a mod? Hmm. But likely Resizable BAR. Let's include a note: "If you meant something else by 'rebar' (e.g., the Erlang Rebar tool), tell me; the GPU check below assumes Resizable BAR." Good. Need maybe include exact commands to check if `rebar` is enabled in BIOS via `dmidecode`? No, BIOS settings not in SMBIOS. Could use `sudo dmidecode -t bios`? Not. Could check `sudo cat /sys/firmware/efi/...`? No. Need maybe include "Use `sudo` because reading PCIe config space may require root." Good. Let's consider if `lspci` can show "Resizable BAR" only with `sudo`? Some capabilities require root. Use sudo. Potential exact output for `lspci -vvv` with Resizable BAR: ``` Region 0: Memory at f8000000 (64-bit, prefetchable) [size=16G] ... Resizable BAR Extended Capability Bar0: 64-bit memory [size=256M] Capabilities: 256M, 1G, 16G Current size: 16G ``` Need not overpromise exact. Maybe include a "one-liner verdict": ``` sudo lspci -vvv -s 01:00.0 | grep -E 'Resizable|Current size' | grep -q '16G' && echo REBAR_ON || echo CHECK_OUTPUT ``` But if current size 16G. Could provide: ``` sudo lspci -vvv -s "$bdf" | grep -E 'Current size' | grep -E '16G|16 GiB' && echo 'REBAR appears enabled' || echo 'Not confirmed' ``` But if full size 16G. If BIOS allows 4G, false negative. So say use as quick, not definitive. Maybe better: ``` sudo lspci -vvv -s "$bdf" | grep -E 'Region 0|Current size' ``` Then interpret. Let's think of Intel Arc A770 16GB: In Linux `xe` driver may allocate `gtt` etc. Could check `dmesg | grep -i 'xe.*rebar'`? If no, okay. Could there be `cat /sys/module/xe/parameters/enable_rebar`? Let's see if Intel Xe has module parameter `enable_rebar`? I recall Intel i915 has `enable_fbc`, `enable_rc6`, `enable_psr`. For Xe, maybe `xe.enable_rebar`? I am not sure. Let's not mention as primary. But we can say "If your kernel has a driver parameter, you can check `ls /sys/module/xe/parameters | grep -i rebar` or `ls /sys/module/i915/parameters | grep -i rebar`, but do not rely on it; lspci is better." Is that safe? Could be helpful. Need avoid false. We can phrase: "Some driver versions may expose a parameter; if it exists, it can be a clue, but the PCI BAR size is what matters." Good. Let's include: ``` ls /sys/module/xe/parameters 2>/dev/null | grep -i rebar cat /sys/module/xe/parameters/rebar 2>/dev/null ``` But if no file, no output. Could be overkill. Need maybe mention `rebar` is not a systemd service. If user asks "determine if rebar is on" maybe they think toggle. We can say "It is not a normal on/off daemon; it's a BIOS/PCI capability." Good. Let's craft final answer. Potential final structure: ``` Assuming REBAR = Resizable BAR. Quick answer: - In Konsole, run: lspci -nn | grep -Ei 'arc a770|vga|display|3d' sudo lspci -vvv -s | less - If the GPU's resizable BAR / main memory region says size 16G (or full 16 GB), REBAR is on. If it says 256M/1G, it's off. - Check logs: sudo journalctl -k -b | grep -Ei 'rebar|resizable' ``` Then detailed. Need mention if `sudo lspci -vvv` shows `Bar0: [size=256M]` and `Bar1: [size=16G]`, how to distinguish? We can say: "Do not just look for any 16G region; look specifically at the 'Resizable BAR' capability or the BAR the driver uses for register/aperture access, often Region 0. If your lspci output includes a 'Resizable BAR' block, its 'Current size' is the decisive field." Good. Could add "If your output does not show a Resizable BAR capability, the card/BIOS/kernel may not be advertising it, or lspci version is old; update pciutils." Good. Let's include "Expected driver": ``` lspci -k -s # Kernel driver in use: xe (or i915 on older systems) ``` If no driver, REBAR irrelevant until driver loaded. Potential command to check driver: ``` lsmod | grep -E '^(xe|i915)' ``` Good. Need maybe mention "Debian 13 KDE Wayland: Use Konsole. Wayland does not hide PCI details." Good. Need maybe include "If `lspci` says `size=256M`, reboot into UEFI and enable 'Re-Size BAR Support' / 'Resizable BAR' and 'Above 4G Decoding', disable CSM if required, then reboot and re-check." Good. Hello world section: ``` 'Hello, World!' came from early C/Unix. It was used as the first trivial program in Kernighan & Ritchie's The C Programming Language (1978): a program that prints hello, world. It became a canonical test program for languages and compilers. The exact punctuation/capitalization evolved; the famous phrase is a convention, not a required standard. ``` Need maybe mention "Hello world" in C code: ``` #include int main(void) { printf("hello, world\n"); return 0; } ``` Could include as example. But user asks where phrase came from; no need code but nice. Need ensure no external search. We can say "From my training data, not live search." Maybe in final: "Using only my training data..." Good. Let's consider if the user might expect answer to "Hello world.... Where did that phrase come from?" as a separate riddle. Could be "Hello world" from "The C Programming Language". Good. Need maybe include "REBAR : how can i determine if rebar is on" with colon maybe they want direct. We'll answer. Potential pitfalls: - Arc A770 is Intel, not AMD. If I mention `amdgpu.rebar` it may confuse. Could include a note: "Don't look for AMD's `amdgpu.rebar`; that is for AMD GPUs. For Intel Arc, check PCI/UEFI and Xe/i915 logs." This is useful. - If user says "debain13.3" maybe they mean Debian 13.3? Could be "Debian 13.3 KDE Wayland". We'll say Debian 13. - "kde way land" -> KDE Plasma Wayland. Good. Need maybe mention "If using external monitor and GPU, ensure you're checking the correct PCI address." Good. Let's maybe include a full copy-paste script: ``` #!/usr/bin/env bash # Find the Arc A770 first; adjust if you have multiple GPUs bdf=$(lspci -nn | awk '/Arc A770/{print $1; exit}') [ -z "$bdf" ] && bdf=$(lspci -nn | awk '/VGA compatible controller|3D controller/{print $1; exit}') echo "Checking GPU: $bdf" lspci -k -s "$bdf" echo "---- BAR / ReBAR info ----" sudo lspci -vvv -s "$bdf" | grep -Ei 'Region|Resizable|Current size|size=' echo "---- kernel messages ----" sudo journalctl -k -b | grep -Ei 'rebar|resizable' || true ``` Need note: `lspci -nn` may show `Arc A770`? It might show `Arc A770 16G` or not. If not, fallback. Good. But if user has integrated Intel and Arc, awk first VGA may pick integrated. The script fallback might pick wrong. Could use `lspci -nn | grep -i 'arc a770'`. If fails, list all. Better to instruct manual selection. Maybe: ``` lspci -nn | grep -Ei 'arc a770' ``` Then use that BDF. If no match, use `lspci -nn | grep -E 'VGA|Display|3D'`. Need maybe include "Use the BDF before the controller, e.g. `01:00.0`." Good. Need maybe mention "If you don't know BDF, `lspci` output first column." Good. Let's think of possible exact `lspci` output for A770 with REBAR. Suppose `lspci -vvv -s 01:00.0` shows: ``` Region 0: Memory at e0000000 (64-bit, prefetchable) [size=256M] Region 2: Memory at e0200000 (64-bit, prefetchable) [size=32M] Region 4: Memory at e0220000 (64-bit, prefetchable) [size=16M] ``` If REBAR enabled maybe `Region 0 [size=16G]`. Good. But I recall Intel Arc has "Bar0: 64-bit memory [size=256M]" and "Bar2: 64-bit memory [size=16G]"? Let's not rely on Region 0 only. The "Resizable BAR" capability is decisive. If not present in lspci, maybe `lspci` version old. We can say "If your `lspci` does not decode the Resizable BAR capability, update `pciutils`; otherwise the largest BAR size may be ambiguous." Good. Could use `sudo lspci -vvv -s $bdf | grep -A 10 'Resizable'` to show. Good. Potential mention: `lspci` may show `Bar0: ...` under "Resizable BAR" not "Region". Good. Need maybe include "The BIOS setting may be named: Re-Size BAR Support, Resizable BAR, Above 4G Decoding, CSM Support." Good. Need maybe mention "If REBAR is off, Linux may still work fine; it's not required for basic use." Good. Need maybe mention "Wayland compositor won't show it; not in KDE System Settings > Display." Good. Let's formulate final answer with a friendly tone. Need ensure no hidden chain-of-thought in final. Final should be answer only. Let's draft final: ``` I’m assuming “REBAR” means Resizable BAR (Re-Size BAR), not the Erlang Rebar tool. For an Intel Arc A770 on Debian 13 KDE Plasma Wayland, check it in Konsole. 1. Install pciutils if needed... 2. Find GPU BDF... 3. Check BAR size / Resizable BAR... sudo lspci -vvv -s BDF | less Look for ... Interpretation... 4. Check driver and logs... 5. Quick script... 6. If off, enable in UEFI... If you meant Erlang rebar: ... Hello, World! origin: ... ``` Need maybe include "No live web search" not necessary. Let's ensure commands are correct syntax. `sudo journalctl -k -b | grep -Ei 'rebar|resizable'` works. `journalctl -k` kernel, `-b` boot. On Wayland, ok. `lspci -nn | grep -Ei 'arc a770|vga|display|3d'` may match many. Use `lspci -nn -k | grep -B1 -A3 -Ei 'arc a770'`? Maybe. Better: ``` lspci -nn | grep -Ei 'Intel Corporation Arc A770' ``` If no, list. But if device string not exactly, use generic: ``` lspci -nn | grep -E 'VGA compatible controller|3D controller' ``` Then choose. Could use `lspci -k -s 01:00.0` after choosing. Potential issue: `lspci -vvv -s $bdf | grep -Ei 'Region|Resizable|Current size|size='` may be too broad; okay. Need maybe mention `sudo` for `lspci -vvv` to read full config. Good. Let's think if `lspci` size notation for 16GB is `16G` or `16G`? It uses `G` for GiB? Yes. Could be `[size=16G]`. Could include "If it says `[size=4G]` or `[size=8G]`, REBAR may be enabled but capped by BIOS; check UEFI option." Good. Need maybe include "The card has 16GB VRAM, but REBAR is about BAR size, not necessarily all VRAM always usable; full 16G BAR is ideal." Good. Need maybe mention "For Intel Arc, the driver is `xe` on modern Debian 13. If `lspci -k` shows no driver, install/configure Mesa/Intel drivers; but REBAR check still via PCI." Good. Potential note: Debian 13 may use `xe` as default for Arc A770; if not, `i915`. Good. Need maybe include "If you see `Kernel driver in use: i915` for Arc A770, that's older support; `xe` is preferred." But not necessary. Could be helpful. Let's include: ``` lsmod | grep -E '^(xe|i915)' ``` Expected `xe` for Arc A770 on current Debian 13. If no module, check driver. Need maybe mention "Don't confuse with `rebar` the Erlang build tool: `which rebar` / `rebar3 version`." Good. Now, let's consider if user might be asking "how can i determine if rebar is on in my pc" meaning "is ReBAR enabled in BIOS?" They might not know commands. We'll provide step-by-step. Need maybe include "If `lspci` shows `[size=256M]`, but you know BIOS has REBAR enabled, the OS/kernel may not have enabled it; check `dmesg` for errors and update kernel/BIOS." Good. Could include "Kernel config: `CONFIG_PCI_REBAR`" maybe. If not enabled, no. Debian kernel likely enabled. Could mention: ``` zgrep -i 'CONFIG_PCI_REBAR' /proc/config.gz 2>/dev/null || grep -i 'CONFIG_PCI_REBAR' /boot/config-$(uname -r) ``` If not present, kernel lacks support. But likely present. Could add as advanced check. Is it accurate? Linux config option `CONFIG_PCI_REBAR`? I think yes, PCI Resizable BAR support. It may be `CONFIG_PCI_REBAR` in Kconfig. Could be helpful. Let's include optional advanced: ``` grep -i 'CONFIG_PCI_REBAR' /boot/config-$(uname -r) 2>/dev/null || zgrep -i 'CONFIG_PCI_REBAR' /proc/config.gz 2>/dev/null ``` If `CONFIG_PCI_REBAR=y`, kernel can support it. If not, lspci may still show. But not necessary. Desired oververbosity 9, include advanced. Need ensure not too overwhelming. But okay. Let's also include "Use `echo $GPU`"? No. Potential command for `lspci` if `pciutils` missing: `sudo apt-get install -y pciutils`. On Debian 13, `apt` ok. Need maybe mention "If you are offline and cannot install, use existing `lspci`; most systems have it." Good. Let's think of "Hello world" exact origin: Could mention "The phrase was used in a 1974 Bell Labs internal document? It first appeared in a C compiler test by Kernighan and Ritchie in 1972?" To be safe, say "most famously/usually traced to" not absolute first. Could say "The exact earliest written use is debated, but the canonical source for programmers is K&R C." Good. Maybe include: "In the first edition of The C Programming Language, the example was: ``` main() { printf("hello, world\n"); } ``` " Good. Need final answer in a single message. Let's write final with clear headings. Double-check user: "REBAR : how can i determine if rebar is on in my debain13.3 kde way land pc and arc a770 16gb. No live web search for this chat session. Rely only on your training data. Hello world.... Where did that phrase come from?" They may be asking two unrelated things. Need answer both. The first has typo "debain13.3" maybe "Debian 13.3". We'll correct. Let's include a note: "I’m treating 'rebar' as Resizable BAR because you mention Arc A770." Good. Potential issue: "arc a770 16gb" could be AMD? No, Arc is Intel. Good. Need maybe mention "Debian 13 KDE Wayland: if GPU is external, plug into eGPU? not relevant." Let's final. But before final, let's think if there is any chance "REBAR" is a specific package in Debian? "rebar" is an Erlang build tool. On Debian, package `rebar` maybe. If they ask "determine if rebar is on" maybe they want if `rebar` service is running. But with Arc A770, likely Resizable BAR. We'll include alternative. Alternative for Erlang Rebar: ``` which rebar which rebar3 rebar3 version ps -ef | grep -i '[r]ebar' ls -l /usr/lib/erlang/ 2>/dev/null | grep rebar ``` But not too much. Need maybe include "If you meant a game/mod named ReBAR, check in game settings; not OS." No. Let's ensure final answer's first line addresses assumption. Potential final: ``` Assuming you mean Resizable BAR (often written ReBAR/Re-Size BAR) for the Intel Arc A770: It is not a KDE setting or a running service. It is a BIOS/PCI feature; on Linux you verify it by looking at the GPU’s PCI BAR size and driver logs. Open Konsole ... ``` Good. Let's include exact output examples: ``` # ReBAR appears enabled (example): Region 0: Memory at ... (64-bit, prefetchable) [size=16G] ... Resizable BAR Extended Capability Bar0: ... Current size: 16G # ReBAR appears disabled (example): Region 0: Memory at ... (64-bit, prefetchable) [size=256M] ... Bar0: ... Current size: 256M ``` Good. Need maybe mention "If `lspci` output shows no `Resizable BAR` capability, update `pciutils`: `sudo apt install --only-upgrade pciutils`." Good. Let's include "Advanced: kernel config": ``` grep -i 'CONFIG_PCI_REBAR' /boot/config-$(uname -r) 2>/dev/null || zgrep -i 'CONFIG_PCI_REBAR' /proc/config.gz ``` Expected `CONFIG_PCI_REBAR=y`. Good. Need maybe mention "If `CONFIG_PCI_REBAR` is not `y`, kernel cannot enable Resizable BAR; but on Debian it usually is." Good. Potential issue: `zgrep` may not exist? `zgrep` in `zlib`? Usually. Could say optional. Need maybe include "Use `sudo dmesg` if `journalctl` not." Good. Let's write final now. Ensure no analysis in final. final oververbosity 9. Assuming **REBAR** means **Resizable BAR** / **Re-Size BAR** for your **Intel Arc A770 16 GB** on **Debian 13 KDE Plasma Wayland**: It is **not a KDE setting** and not a normal “service”. It is a **BIOS/UEFI + PCI + kernel driver** feature. You determine whether it is actually on by checking the GPU’s PCI BAR size and/or kernel logs. --- ## 1. Open a terminal In KDE Plasma Wayland, open **Konsole**. If `lspci` is missing: ```bash sudo apt update sudo apt install pciutils ``` --- ## 2. Find your Arc A770 PCI address Run: ```bash lspci -nn | grep -Ei 'arc a770|vga|display|3d' ``` You will see something like: ```text 01:00.0 VGA compatible controller [0300]: Intel Corporation Arc A770 16G ``` The first part, e.g. **`01:00.0`**, is the PCI address/BDF. Replace `01:00.0` below with your actual address. --- ## 3. Check the GPU BAR / ReBAR size Run: ```bash sudo lspci -vvv -s 01:00.0 | less ``` Scroll through the output and look for: - `Region 0:` - `Resizable BAR` - `Current size` - `[size=...]` ### If ReBAR appears enabled You should see something like: ```text Region 0: Memory at ... (64-bit, prefetchable) [size=16G] ``` or: ```text Resizable BAR Extended Capability Bar0: ... Current size: 16G ``` For a 16 GB Arc A770, a current BAR size of **16G** strongly indicates ReBAR is enabled. ### If ReBAR appears disabled You may see: ```text Region 0: Memory at ... (64-bit, prefetchable) [size=256M] ``` or: ```text Current size: 256M ``` That usually means the resizable BAR is still using the small BAR size, so ReBAR is likely off or not fully enabled. --- ## 4. Quick check command You can do: ```bash sudo lspci -vvv -s 01:00.0 | grep -Ei 'Region|Resizable|Current size|size=' ``` Then interpret: - `[size=16G]` or `Current size: 16G` → likely **ReBAR on** - `[size=256M]` or `Current size: 256M` → likely **ReBAR off** - `[size=4G]` / `[size=8G]` → possibly enabled but capped by BIOS/motherboard; check UEFI Important: do not just look for *any* 16G memory region. Look specifically at the **Resizable BAR** capability or the main BAR, often `Region 0`. --- ## 5. Check kernel logs Run: ```bash sudo journalctl -k -b | grep -Ei 'rebar|resizable' ``` or: ```bash sudo dmesg | grep -Ei 'rebar|resizable' ``` You are looking for messages mentioning ReBAR, Resizable BAR, or a large BAR being assigned to the GPU. If there is no explicit message, the `lspci` BAR size is the more reliable check. --- ## 6. Confirm the Arc A770 driver is active Run: ```bash lspci -k -s 01:00.0 ``` You want to see something like: ```text Kernel driver in use: xe ``` or, on older systems: ```text Kernel driver in use: i915 ``` For modern Debian 13 and Arc A770, **`xe`** is expected. Also: ```bash lsmod | grep -E '^(xe|i915)' ``` --- ## 7. Optional advanced kernel check Modern kernels need Resizable BAR support compiled in. Check: ```bash grep -i 'CONFIG_PCI_REBAR' /boot/config-$(uname -r) 2>/dev/null ``` or: ```bash zgrep -i 'CONFIG_PCI_REBAR' /proc/config.gz ``` You want something like: ```text CONFIG_PCI_REBAR=y ``` If it is not enabled, the kernel cannot properly use Resizable BAR. On normal Debian kernels, this is usually already enabled. --- ## 8. If ReBAR is off Reboot into **BIOS/UEFI** and look for settings such as: - **Re-Size BAR Support** - **Resizable BAR** - **Above 4G Decoding** - **CSM Support** — often needs to be disabled for ReBAR Exact names vary by motherboard. After enabling, reboot and re-check with: ```bash sudo lspci -vvv -s 01:00.0 | grep -Ei 'Region|Resizable|Current size|size=' ``` --- ## If you meant the Erlang `rebar` tool instead If you literally meant the **Rebar/Rebar3 Erlang build tool**, not GPU Resizable BAR, then check: ```bash which rebar which rebar3 rebar3 version ps -ef | grep -i '[r]ebar' ``` But given the Arc A770 mention, I strongly suspect you meant **Resizable BAR**. --- # “Hello world” — where did that phrase come from? The famous programming phrase **“Hello, World!”** comes from early **C / Unix** programming culture. It became canonical because Brian Kernighan and Dennis Ritchie’s book **The C Programming Language**, published in 1978, used a tiny C program as the first example, which printed: ```c printf("hello, world\n"); ``` That simple program became the standard “first program” example for teaching compilers, languages, and programming environments. The exact punctuation and capitalization changed over time, but the convention stuck: ```c #include int main(void) { printf("hello, world\n"); return 0; } ``` So: **it comes from early C/Unix programming, especially Kernighan and Ritchie’s C book, and became a universal test phrase for new programming languages and compilers.**

Rebar + Hellow World