Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst
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UVD 4.2 doesn't work at all when DPM is disabled because
the SMU is responsible for ungating it. So, Linux fails
to boot with CIK GPUs when using the amdgpu.dpm=0 parameter.
Fix this by returning -ENOENT from uvd_v4_2_early_init()
when amdgpu_dpm isn't enabled.
Note: amdgpu.dpm=0 is often suggested as a workaround
for issues and is useful for debugging.
Fixes: a2e73f56fa62 ("drm/amdgpu: Add support for CIK parts")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
On a specific Radeon R9 390X board, the GPU can "randomly" hang
while gaming. Initially I thought this was a RADV bug and tried
to work around this in Mesa:
commit 8ea08747b86b ("radv: Mitigate GPU hang on Hawaii in Dota 2 and RotTR")
However, I got some feedback from other users who are reporting
that the above mitigation causes a significant performance
regression for them, and they didn't experience the hang on their
GPU in the first place.
After some further investigation, it turns out that the problem
is that the highest SCLK DPM level on this board isn't stable.
Lowering SCLK to 1040 MHz (from 1070 MHz) works around the issue,
and has a negligible impact on performance compared to the Mesa
patch. (Note that increasing the voltage can also work around it,
but we felt that lowering the SCLK is the safer option.)
To solve the above issue, add an "sclk_cap" field to smu7_hwmgr
and set this field for the affected board. The capped SCLK value
correctly appears on the sysfs interface and shows up in GUI
tools such as LACT.
Fixes: 9f4b35411cfe ("drm/amd/powerplay: add CI asics support to smumgr (v3)")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
In ci_populate_dw8() we currently just read a value from the SMU
and then throw it away. Instead of throwing away the value,
we should use it to fill other fields in DW8 (like radeon).
Otherwise the value of the other fiels is just cleared when
we copy this data to the SMU later.
Fixes: 9f4b35411cfe ("drm/amd/powerplay: add CI asics support to smumgr (v3)")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Follow what radeon did and what amdgpu does for other GPUs with SMU7.
Fixes: 9f4b35411cfe ("drm/amd/powerplay: add CI asics support to smumgr (v3)")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
There is no AMD GPU with the ID 0x66B0, this looks like a typo.
It should be 0x67B0 which is actually part of the PCI ID list,
and should use the Hawaii XT powertune defaults according to
the old radeon driver.
Fixes: 9f4b35411cfe ("drm/amd/powerplay: add CI asics support to smumgr (v3)")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
It looks like this was written for an old version of DC (DAL)
and was never adapted afterwards. This was non-functional
because it relied on the "dal_power_level" field which was
never assigned anywhere in the code base.
Also, it was not implemented for CI ASICs.
Now superseded by the newer voltage dependency on display
clock table added by the previous commit, let's remove.
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
The DCE (display controller engine) requires a minimum voltage
in order to function correctly, depending on which clock level
it currently uses.
Add a new table that contains display clock frequency levels
and the corresponding required voltages. The clock frequency
levels are taken from DC (and the old radeon driver's voltage
dependency table for CI in cases where its values were lower).
The voltage levels are taken from the following function:
phm_initializa_dynamic_state_adjustment_rule_settings().
Furthermore, in case of CI, call smu7_patch_vddc() on the new
table to account for leakage voltage (like in radeon).
Use the display clock value from amd_pp_display_configuration
to look up the voltage level needed by the DCE. Send the
voltage to the SMU via the PPSMC_MSG_VddC_Request command.
The previous implementation of this feature was non-functional
because it relied on a "dal_power_level" field which was never
assigned; and it was not at all implemented for CI ASICs.
I verified this on a Radeon R9 M380 which previously booted to
a black screen with DC enabled (default since Linux 6.19), but
now works correctly.
Fixes: 599a7e9fe1b6 ("drm/amd/powerplay: implement smu7 hwmgr to manager asics with smu ip version 7.")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
There are two known cases where MCLK DPM can causes issues:
Radeon R9 M380 found in iMac computers from 2015.
The SMU in this GPU just hangs as soon as we send it the
PPSMC_MSG_MCLKDPM_Enable command, even when MCLK switching is
disabled, and even when we only populate one MCLK DPM level.
Apply workaround to all devices with the same subsystem ID.
Radeon R7 260X due to old memory controller microcode.
We only flash the MC ucode when it isn't set up by the VBIOS,
therefore there is no way to make sure that it has the correct
ucode version.
I verified that this patch fixes the SMU hang on the R9 M380
which would previously fail to boot. This also fixes the UVD
initialization error on that GPU which happened because the
SMU couldn't ungate the UVD after it hung.
Fixes: 86457c3b21cb ("drm/amd/powerplay: Add support for CI asics to hwmgr")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
When MCLK DPM is disabled for any reason, populate the MCLK
table with the highest MCLK DPM level, so that the ASIC can
use the highest possible memory clock to get good performance
even when MCLK DPM is disabled.
Fixes: 9f4b35411cfe ("drm/amd/powerplay: add CI asics support to smumgr (v3)")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Thanks to "drm/ttm: rework pipelined eviction fence handling", ttm
can deal correctly with moves and evictions being executed from
different contexts.
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Acked-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
The control stack size is calculated based on the number of CUs and
waves, and is then aligned to PAGE_SIZE. When the resulting control
stack size is aligned to 64 KB, GPU hangs and queue preemption
failures are observed while running RCCL unit tests on systems with
more than two GPUs.
amdgpu 0048:0f:00.0: amdgpu: Queue preemption failed for queue with
doorbell_id: 80030008
amdgpu 0048:0f:00.0: amdgpu: Failed to evict process queues
amdgpu 0048:0f:00.0: amdgpu: GPU reset begin!. Source: 4
amdgpu 0048:0f:00.0: amdgpu: Queue preemption failed for queue with
doorbell_id: 80030008
amdgpu 0048:0f:00.0: amdgpu: Failed to evict process queues
amdgpu 0048:0f:00.0: amdgpu: Failed to restore process queues
This issue is observed on both 4 KB and 64 KB system page-size
configurations.
This patch fixes the issue by aligning the control stack size to
AMDGPU_GPU_PAGE_SIZE instead of PAGE_SIZE, so the control stack size
will not be 64 KB on systems with a 64 KB page size and queue
preemption works correctly.
Additionally, In the current code, wg_data_size is aligned to PAGE_SIZE,
which can waste memory if the system page size is large. In this patch,
wg_data_size is aligned to AMDGPU_GPU_PAGE_SIZE. The cwsr_size, calculated
from wg_data_size and the control stack size, is aligned to PAGE_SIZE.
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Donet Tom <donettom@linux.ibm.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Use TTM_NUM_MOVE_FENCES as an upperbound of how many fences
ttm might need to deal with moves/evictions.
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Acked-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This makes clear of different BOs run in parallel. Partial jobs to
clear a single BO still execute sequentially.
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
No functional change for now, as we always allocate a single entity.
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Acked-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
No functional change for now, as we always allocate a single entity
and use it everywhere.
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
there is an abnormal case that When a process re-opens kfd
with different mm_struct(execve() called by user), the
allocated p->kobj will be freed, but missed setting it to NULL,
that will cause sysfs/kernel crash with NULL pointers in p->kobj
on kfd_process_remove_sysfs() when releasing process, and the
similar error on kfd_procfs_del_queue() as well.
Signed-off-by: Eric Huang <jinhuieric.huang@amd.com>
Reviewed-by: Kent Russell <kent.russell@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>