[U-Boot] [PATCH 1/1] efi_loader: remove efi_exit_caches()

[Tom Rini]

On Sun, Jul 21, 2019 at 10:46:24AM +0100, Peter Robinson wrote:
> > >>> On Fri, Jul 19, 2019 at 7:28 PM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > >>>>
> > >>>> In GRUB before 2.04 a bug existed which did not allow booting some ARM32
> > >>>> boards if U-Boot did not disable caches, cf.
> > >>>> https://lists.linaro.org/pipermail/cross-distro/2019-July/000933.html
> > >>>>
> > >>>> In ExitBootServices() we were disabling the caches by calling
> > >>>> cleanup_before_linux(). This workaround is not needed anymore.
> > >>>
> > >>> Do we want to remove this straight away? A lot of distributions will
> > >>> take time to move to grub 2.04 because it's been a long time between
> > >>> grub releases so they'll have quite a patch delta to re-align to the
> > >>> new release. Fedora for example will rebase to grub 2.04 in Fedora 32
> > >>> which will start development end of August but won't be released until
> > >>> next year.
> > >>
> > >> As described below this code does not remove any functionality that was
> > >> active in U-Boot v2019.04 or v2019.07.
> > >>
> > >> I can see nothing in https://fedoraproject.org/wiki/Updates_Policy
> > >> stopping GRUB 2.04 from being made available for stable Fedora releases.
> > >
> > > The maintainers believe that it's too intrusive to land now and they
> > > want maximum testing time before it gets to stable users, funnily
> > > enough people don't like it when their machines cease to boot.
> >
> > Why should anybody's machines cease to boot?
> >
> > If Fedora does not role out a new U-Boot they are fine. If Fedora roles
> > out a new U-Boot they should role out a matching GRUB and they are fine too.
> >
> > The venturous who build their own U-Boot should know how to role back
> > their system if needed.
> 
> You've clearly never maintained a distribution across 1000s of device
> types and 100s of thousands of users.
> 
> We will be shipping Fedora 31 with U-Boot 2019.10 and the current
> version of grub that the maintainers wish to support, if that requires
> me to revert a number of your changes I will, which will be an
> inconvenience and probably take more time than I have spare but I will
> survive. I find it strange you fix one OS only to break another. How
> will this work for users that want to boot a newly released device
> which has recently added U-Boot support to an already released stable
> OS?
> 
> If you wish to actively break currently working use cases that's your
> prerogative that is your choice but I find breaking currently working
> use cases without a reasonable window to migrate dependencies actively
> hostile which has tended to not be the way U-Boot has worked in the
> past for such things as DM, so breaking a interface to the way OSes
> boot IMO is even worse.

OK, we have a problem here.  A better example than DM would be the
various work-arounds we have (or carried for ages) to allow using newer
U-Boot with various old and broken kernels.  So no, we need to keep this
work-around for a long while.  What's the EOL date for any Linux
distribution that uses this broken grub?  The first U-Boot release post
that EOL date is when we can drop this particular bit of work-around
code.

-- 
Tom
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.denx.de/pipermail/u-boot/attachments/20190722/fe6f2833/attachment.sig>