[JAMMY][SRU][PATCH 0/4] Backport support to tolerate ZSTD compressed firmware files

[Tim Gardner]

On 7/26/23 7:01 AM, Dimitri John Ledkov wrote:
> On Wed, 26 Jul 2023 at 13:42, Tim Gardner <tim.gardner at canonical.com> wrote:
>>
>> On 7/25/23 3:15 PM, Dimitri John Ledkov wrote:
>>> [ Impact ]
>>>
>>>    * To ensure reliable dist-upgrades in case of partial upgrades or
>>>      upgrade failures, it is desirable for LTS GA kernel to support
>>>      features that next-LTS GA kernel will rely on.
>>>
>>>    * Specifically it is being discussed to switch linux-firmware to ZSTD
>>>      compressed one
>>>
>>>    * To ensure that failed dist-upgrades can still boot after-partial
>>>      upgrade it is desirable to suppport zstd compressed firmware
>>>
>>> [ Test Plan ]
>>>
>>>    * Boot new build of GA linux kernel with
>>>      CONFIG_FW_LOADER_COMPRESS_ZSTD
>>>
>>>    * Check that existing firmware files loaded on a given machine can be
>>>      compressed with zstd and still loaded by this kernel
>>>
>>>    * Check that depmod / initramfs-tools all support .zst compressed
>>>      firmware
>>>
>>> [ Where problems could occur ]
>>>
>>>    * Once this is inroduced in jammy-GA kernel it may cripple into
>>>      focal-hwe kernels too, and people may start relying on this feature
>>>      despite not universally supported by all other focal kernels. This
>>>      should be trivial to catch in SRUs for example, do not accept SRUs
>>>      of firmwares that ship themselves as .zst in Jammy and lower.
>>>
>>> [ Other Info ]
>>>
>>>    * See
>>>      https://lists.ubuntu.com/archives/ubuntu-devel/2023-July/042652.html
>>>
>>> Dimitri John Ledkov (2):
>>>     UBUNTU: SAUCE: Backport ZSTD-compressed firmware files to old ZSTD API
>>>     UBUNTU: [Config] Enable FW_LOADER_COMPRESS_ZSTD by default
>>>
>>> Randy Dunlap (1):
>>>     firmware_loader: EXTRA_FIRMWARE does not support compressed files
>>>
>>> Takashi Iwai (1):
>>>     firmware: Add the support for ZSTD-compressed firmware files
>>>
>>>    debian.master/config/annotations     |  3 ++
>>>    drivers/base/firmware_loader/Kconfig | 27 ++++++++--
>>>    drivers/base/firmware_loader/main.c  | 76 ++++++++++++++++++++++++++--
>>>    3 files changed, 98 insertions(+), 8 deletions(-)
>>>
>>
>> Shouldn't you merge 'UBUNTU: SAUCE: Backport ZSTD-compressed firmware
>> files to old ZSTD API' into ' firmware: Add the support for
>> ZSTD-compressed firmware files' and call it  a backport ? Otherwise
>> you've introduced a commit that won't compile.
> 
> Correct if those two commits are squished together, it becomes a
> backport. However, to me it seems more clear to present my work like
> this, at least for the review.
> Or do people routinely interdiff the patch with upstream one to see
> the backport diff progmatically?
> 

Yes, the latter. Otherwise its up to the maintainer to squash the 
patches together which can add up to a lot of work.

-- 
-----------
Tim Gardner
Canonical, Inc