question about one of your ubuntu patch

Tue Sep 1 12:20:44 UTC 2020

> Hi Thadeu,
> 
> I just found a patch in
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1857158, "rtc: disable
> uie before setting time and enable after"--7e7c005b4b1f1f169bcc. It's
> in v4.19.89. But it's not patched in Ubuntu-4.15.0-76.86,which is issued at
> Jan 17 2020.
> Ubuntu-4.15.0-76.86 contains the commit in the "Fixes:"
> in 7e7c005b4b1f1f169bcc, which means that ubuntu introduces the bug. It's
> necessary to be patched. And the patch is also in the list of
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1857158. I thought all
> the patches
> in that website are to be added in ubuntu. Why is not it added in ubuntu?
> Is there any other rules?

That patch was added to Bionic 4.15.0-88.88. If you look at LP: #1857158
(comment #1) it will tell you which kernel version fixed the bug.

We have quite a backlog and keeping kernels up to date is time consuming so it
just took us a while to pull the commits into Bionic.

...Juerg

> Thanks
> 
> On Wed, Aug 12, 2020 at 9:42 PM David Lee <saynice111 at gmail.com> wrote:
> 
> > 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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