From: Dave Airlie airlied@redhat.com
A recent snafu where Intel ignored upstream feedback on a firmware change, led to a late rc6 fix being required. In order to avoid this in the future we should document some expectations around linux-firmware.
I was originally going to write this for drm, but it seems quite generic advice.
I'm cc'ing this quite widely to reach subsystems which use fw a lot.
Signed-off-by: Dave Airlie airlied@redhat.com --- Documentation/driver-api/firmware/core.rst | 1 + .../firmware/firmware-usage-guidelines.rst | 34 +++++++++++++++++++ 2 files changed, 35 insertions(+) create mode 100644 Documentation/driver-api/firmware/firmware-usage-guidelines.rst
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..34d2412e78c6 --- /dev/null +++ b/Documentation/driver-api/firmware/firmware-usage-guidelines.rst @@ -0,0 +1,34 @@ +=================== +Firmware Guidelines +=================== + +Drivers that use firmware from linux-firmware should attempt to follow +the rules in this guide. + +* Firmware should 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 + major/minor/patch versions should be stored in a header in the + firmware file for the driver to detect any non-ABI fixes/issues. The + firmware files in linux-firmware should be overwritten with the newest + compatible major version. Newer major version firmware should remain + compatible with all kernels that load that major number. + +* Users should *not* have to install newer firmware to use existing + hardware when they install a newer kernel. If the hardware isn't + enabled by default or under development, 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 should be updated with the security fix, and 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. +