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authorLinus Torvalds <torvalds@linux-foundation.org>2022-08-04 21:31:20 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-08-04 21:31:20 +0300
commitcfeafd94668910334a77c9437a18212baf9f5610 (patch)
treeb863f4f9688ac141f65b62a69addd0f9bfcc2126 /Documentation/driver-api/firmware
parent228dfe98a313f6b6bff5da8b2c5e650e297ebf1a (diff)
parent273aaa24369cb8d0f246bb16f7122b91a1ef5188 (diff)
downloadlinux-cfeafd94668910334a77c9437a18212baf9f5610.tar.xz
Merge tag 'driver-core-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core / kernfs updates from Greg KH: "Here is the set of driver core and kernfs changes for 6.0-rc1. The "biggest" thing in here is some scalability improvements for kernfs for large systems. Other than that, included in here are: - arch topology and cache info changes that have been reviewed and discussed a lot. - potential error path cleanup fixes - deferred driver probe cleanups - firmware loader cleanups and tweaks - documentation updates - other small things All of these have been in the linux-next tree for a while with no reported problems" * tag 'driver-core-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (63 commits) docs: embargoed-hardware-issues: fix invalid AMD contact email firmware_loader: Replace kmap() with kmap_local_page() sysfs docs: ABI: Fix typo in comment kobject: fix Kconfig.debug "its" grammar kernfs: Fix typo 'the the' in comment docs: driver-api: firmware: add driver firmware guidelines. (v3) arch_topology: Fix cache attributes detection in the CPU hotplug path ACPI: PPTT: Leave the table mapped for the runtime usage cacheinfo: Use atomic allocation for percpu cache attributes drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist MAINTAINERS: Change mentions of mpm to olivia docs: ABI: sysfs-devices-soc: Update Lee Jones' email address docs: ABI: sysfs-class-pwm: Update Lee Jones' email address Documentation/process: Add embargoed HW contact for LLVM Revert "kernfs: Change kernfs_notify_list to llist." ACPI: Remove the unused find_acpi_cpu_cache_topology() arch_topology: Warn that topology for nested clusters is not supported arch_topology: Add support for parsing sockets in /cpu-map arch_topology: Set cluster identifier in each core/thread from /cpu-map arch_topology: Limit span of cpu_clustergroup_mask() ...
Diffstat (limited to 'Documentation/driver-api/firmware')
-rw-r--r--Documentation/driver-api/firmware/core.rst1
-rw-r--r--Documentation/driver-api/firmware/firmware-usage-guidelines.rst44
2 files changed, 45 insertions, 0 deletions
diff --git a/Documentation/driver-api/firmware/core.rst b/Documentation/driver-api/firmware/core.rst
index 1d1688cbc078..803cd574bbd7 100644
--- a/Documentation/driver-api/firmware/core.rst
+++ b/Documentation/driver-api/firmware/core.rst
@@ -13,4 +13,5 @@ documents these features.
direct-fs-lookup
fallback-mechanisms
lookup-order
+ firmware-usage-guidelines
diff --git a/Documentation/driver-api/firmware/firmware-usage-guidelines.rst b/Documentation/driver-api/firmware/firmware-usage-guidelines.rst
new file mode 100644
index 000000000000..fdcfce42c6d2
--- /dev/null
+++ b/Documentation/driver-api/firmware/firmware-usage-guidelines.rst
@@ -0,0 +1,44 @@
+===================
+Firmware Guidelines
+===================
+
+Users switching to a newer kernel should *not* have to install newer
+firmware files to keep their hardware working. At the same time updated
+firmware files must not cause any regressions for users of older kernel
+releases.
+
+Drivers that use firmware from linux-firmware should follow the rules in
+this guide. (Where there is limited control of the firmware,
+i.e. company doesn't support Linux, firmwares sourced from misc places,
+then of course these rules will not apply strictly.)
+
+* Firmware files shall be designed in a way that it allows checking for
+ firmware ABI version changes. It is recommended that firmware files be
+ versioned with at least a major/minor version. It is suggested that
+ the firmware files in linux-firmware be named with some device
+ specific name, and just the major version. The firmware version should
+ be stored in the firmware header, or as an exception, as part of the
+ firmware file name, in order to let the driver detact any non-ABI
+ fixes/changes. The firmware files in linux-firmware should be
+ overwritten with the newest compatible major version. Newer major
+ version firmware shall remain compatible with all kernels that load
+ that major number.
+
+* If the kernel support for the hardware is normally inactive, or the
+ hardware isn't available for public consumption, this can
+ be ignored, until the first kernel release that enables that hardware.
+ This means no major version bumps without the kernel retaining
+ backwards compatibility for the older major versions. Minor version
+ bumps should not introduce new features that newer kernels depend on
+ non-optionally.
+
+* If a security fix needs lockstep firmware and kernel fixes in order to
+ be successful, then all supported major versions in the linux-firmware
+ repo that are required by currently supported stable/LTS kernels,
+ should be updated with the security fix. The kernel patches should
+ detect if the firmware is new enough to declare if the security issue
+ is fixed. All communications around security fixes should point at
+ both the firmware and kernel fixes. If a security fix requires
+ deprecating old major versions, then this should only be done as a
+ last option, and be stated clearly in all communications.
+