question about one of your ubuntu patch

[David Lee]

Hi Thadeu,

we have Kamal do the
great job of tracking commits to 4.14 and 4.19 and make pull requests so
those
can be included in Ubuntu's kernel.

I just measured that there are 13007 commits from 4.15.18 which is
end-of-life in 4.15 stable branch to a specific ubuntu-bionic
version, Ubuntu-4.15.0-76.86. 9830 commits in 13007 also exist in 4.14 lts.
But there is 0 commit which exist in 4.19 lts. Is there anything wrong?
Can you give me more guidance on this?
Thanks


On Tue, Aug 11, 2020 at 12:49 PM David Lee <saynice111 at gmail.com> wrote:

> Hi,
>
> Thanks for your reply. Very helpful to me.
>
> There is no upstream Linux 4.15 stable branch.
>
> There is no upstream linux 4.15 long term support branch. But there is a
> Linux stable branch
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/log/?h=linux-4.15.y
> .
>
> Ubuntu's bionic is based on Linux 4.15. But there is also linux 4.15-linux
> 4.15.18 branch in ubuntu-bionic. And commits in Linux 4.15-4.15.18 in
> ubuntu git is the same as it in Linux git except some ubuntu sauce patches.
>
> Besides, how does ubuntu know if there is a new patch added in upstream?
> And how do ubuntu determine if a patch is necessary for ubuntu?
> Thanks
>
> On Tue, Aug 11, 2020 at 4:32 AM Thadeu Lima de Souza Cascardo <
> cascardo at canonical.com> wrote:
>
>> On Tue, Aug 11, 2020 at 12:33:17AM -0700, David Lee wrote:
>> > Hi,
>> >
>> > I saw your email in the patch "serdev: Fix serdev_uevent failure on ACPI
>> > enumerated serdev-controllers 586ca5b1a90b66eb0a2805c9419683e33d1d418b"
>> in
>> > ubuntu's git repository.
>> > I am surprised to find that this patch in ubuntu git is committed on
>> Apr 12
>> > 10:06:37 2018. But this patch is committed to linux 4.15 stable branch
>> > on Apr 12 12:31:11 2018.
>> > In ubuntu git repository, this patch is also in Linux 4.15 stable
>> branch.
>> > Why a patch is committed before it's added in Linux 4.15 stable branch?
>> >
>> > Thanks
>>
>> Hi, David.
>>
>> There is no upstream Linux 4.15 stable branch. Upstream kernel.org git
>> trees
>> closest to 4.15 are 4.14 and 4.19. Kamal Mostafa, from the Ubuntu Kernel
>> team
>> picks up commits from those trees in order to apply them to Ubuntu bionic
>> kernel tree, which is based on 4.15. As upstream has stopped publishing
>> updates
>> to 4.15 and Ubuntu picked up 4.15 for its Bionic release, we have Kamal
>> do the
>> great job of tracking commits to 4.14 and 4.19 and make pull requests so
>> those
>> can be included in Ubuntu's kernel.
>>
>> But patches are also submitted to Ubuntu's kernel through other ways and
>> for
>> other reasons, like when they fix specific bugs tracked at launchpad. It
>> may
>> happen that such patches match upstream commits that have both landed on
>> Kamal's tree and directly on Ubuntu's tree.
>>
>> And by git's distributed nature, the same patch may be applied on
>> different
>> dates, or it may happen that they are rebased or reapplied, causing them
>> to
>> have different commit ids, and even different commit dates or commit
>> authors,
>> or have had their messages changed because of sign-offs.
>>
>> I didn't investigate the specific case you pointed out, but it may be
>> that with
>> the explanations above, you may find other differences between those two
>> commits that might explain what might have happened.
>>
>> Regards.
>> Thadeu Cascardo.
>>
>
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