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Groups > linux.debian.kernel > #61174

Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers.

Cross-posted to 2 groups.

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On Fri, 2018-06-08 at 12:33 -0700, Geoff Levand wrote:
> On 06/05/2018 12:28 AM, Ian Campbell wrote:
> > On Tue, 2018-06-05 at 02:14 +0100, Ben Hutchings wrote:
> > 
> >> I don't think it's OK to cause a regression like this.  Since this
> is
> >> problem affects a specific known platform, the driver ought to
> >> recognise it and disable itself automatically.
> > 
> > Indeed, while the Fedora bug upthread claims such a patch wouldn't
> be
> > upstreamable, AFAIK it is not uncommon to have such quirks for
> broken
> > firmware based upon DMI identifiers or similar.
> 
> Just to mention it, Mark Salter submitted one of the work-around
> patches
> for the m400 firmware.  The reply from the ACPI maintainer wasn't
> very
> encouraging. See:
> 
>   https://lkml.org/lkml/2018/4/19/1020 (ACPI / scan: Fix regression
> related to X-Gene UARTs)

He said:
> I'm not convinced that making changes to the core ACPI device
> enumeration code in order to cover up for firmware bugs is the right
> approach.

That response seems fair, changing the core ACPI code at that point
indeed doesn't seem correct, especially with a one-off special case
(most such things are table and callback driven).

I think this is probably something for the arch (or perhaps platform)
code to deal with. See for example all the various platform quirks in
arch/x86/kernel/acpi/boot.c, which fixup various wrongness and/or
disable features.

Although I would also note that there seems to be ~200 existing DMI
matches under drivers/acpi, just not in the core device enumeration
code, I don't read Rafael's response as ruling out a fix somewhere in
the ACPI code, just not in the enumeration paths as presented there.

> CONFIG_ACPI_APEI allows for automated error reporting, so it is something
> that is very desirable[...]

I don't think anyone is disputing that, but there are tradeoff to be
made here.

> Is this an acceptable solution?

It should be sent upstream. It at least seems to be a more targetted
fix than the one above.

Has anyone tried to detect this "slave device attached to itself"
situation in a more generic way? Perhaps that would also be worth
discussing with upstream too.

It's an expected consequence of ARM & co's push towards the ACPI model
which effectively requires that the (upstream) kernel must deal with
buggy firmware in the field, just like on x86.

I don't think it is right that the distros should have to carry and
support fixes for this sort of thing, it should be done upstream or by
vendors fixing firmware (and I don't hold out much hope for the latter
if x86 is any indication, especially for a platform now as old as the
m400).

Ian.

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Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-06-01 19:10 +0200
  Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Riku Voipio <riku.voipio@iki.fi> - 2018-06-04 13:10 +0200
    Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-06-04 17:40 +0200
      Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Ben Hutchings <ben@decadent.org.uk> - 2018-06-05 03:20 +0200
        Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Ian Campbell <ijc@debian.org> - 2018-06-05 09:40 +0200
          Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-06-08 21:40 +0200
            Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Ian Campbell <ijc@debian.org> - 2018-06-09 14:20 +0200
              Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-06-13 21:30 +0200
                Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Ian Campbell <ijc@debian.org> - 2018-06-14 11:10 +0200
                Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Riku Voipio <riku.voipio@iki.fi> - 2018-08-06 16:40 +0200
                Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-08-07 00:10 +0200
  Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-09-01 01:00 +0200
    Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Ian Campbell <ijc@debian.org> - 2018-09-02 10:00 +0200
  Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-09-01 02:00 +0200
    Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Ben Hutchings <ben@decadent.org.uk> - 2018-09-04 19:30 +0200
      Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-09-04 20:50 +0200
        Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Riku Voipio <riku.voipio@iki.fi> - 2018-09-05 08:50 +0200
        Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Ben Hutchings <ben@decadent.org.uk> - 2018-09-06 22:30 +0200
  Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-09-20 22:00 +0200
    Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-09-21 17:40 +0200
      Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Ben Hutchings <ben@decadent.org.uk> - 2018-09-22 01:30 +0200
        Bug#900581: linux: Enable Buster kernel features for newer ARM64 servers. Geoff Levand <geoff@infradead.org> - 2018-09-24 19:20 +0200

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