linux-kernel - Re: [PATCH] fix x86 DMI checks for PCI quirks

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Date:	Fri, 2 May 2008 02:19:34 -0700
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Matt Domsch" <Matt_Domsch@...l.com>, akpm@...ux-foundation.org,
	jgarzik@...ox.com, muli@...ibm.com, davej@...hat.com,
	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	bunk@...nel.org, linux-bugs@...l.com, linux-kernel@...r.kernel.org,
	greg@...ah.com, "Jesse Barnes" <jbarnes@...tuousgeek.org>
Subject: Re: [PATCH] fix x86 DMI checks for PCI quirks

On Fri, May 2, 2008 at 12:44 AM, Ingo Molnar <mingo@...e.hu> wrote:
>
>  * Matt Domsch <Matt_Domsch@...l.com> wrote:
>
>  > fix x86 DMI checks for PCI quirks
>  >
>  > http://bugzilla.kernel.org/show_bug.cgi?id=10583
>  > https://bugzilla.redhat.com/show_bug.cgi?id=444791
>  >
>  > Since git commit 08f1c192c3c32797068bfe97738babb3295bbf42 (between
>  > kernels 2.6.22 and 2.6.23), arch/x86/pci/acpi.c has not called
>  > pcibios_scan_root(), which would have called
>  > arch/x86/pci/common.c:dmi_check_system().  This has prevented the
>  > quirks listed in pciprobe_dmi_table[] from being checked and
>  > appropriate action taken.
>
>  ugh ...
>
>
>  > This manifests itself in several Dell and HP servers not automatically
>  > having the pci=bfsort option be applied, as well as Samsung X20 and
>  > Compaq EVO N800c systems needing pci=assign-all-busses was no longer
>  > automatically applied.
>  >
>  > This patch moves the DMI tests into its own file, arch/x86/pci/dmi.c,
>  > and invokes them via subsys_initcall() before pci_acpi_init(),
>  > pci_legacy_init(), and pcibios_init() are called, which may rely upon
>  > these tests having been executed.
>
>  Jesse Barnes (new PCI maintainer) Cc:-ed.
>
>  i'm wondering how we could avoid such mishaps in the future. This was
>  broken from 2.6.23 through 2.6.25 - way too long. Perhaps we should
>  create a known signature of the device tree in user-space, and somehow
>  warn if the kernel changes it? Could this somehow be put into the
>  kernel?
>

please check the patch in x86.git, it should do the same thing, but
put the call in pci_access_init...

commit 9817aa147000086bc11b571620ecc1c73a4a614b
Author: Yinghai Lu <yhlu.kernel@...il.com>
Date:   Mon Apr 14 15:40:37 2008 -0700

    x86 PCI: call dmi_check_pciprobe()

    this change:

    | commit 08f1c192c3c32797068bfe97738babb3295bbf42
    | Author: Muli Ben-Yehuda <muli@...ibm.com>
    | Date:   Sun Jul 22 00:23:39 2007 +0300
    |
    |    x86-64: introduce struct pci_sysdata to facilitate sharing of ->sysdata
    |
    |    This patch introduces struct pci_sysdata to x86 and x86-64, and
    |    converts the existing two users (NUMA, Calgary) to use it.
    |
    |    This lays the groundwork for having other users of sysdata, such as
    |    the PCI domains work.
    |
    |    The Calgary bits are tested, the NUMA bits just look ok.

    replaces pcibios_scan_root with pci_scan_bus_parented...

    but in pcibios_scan_root we have a DMI check:

        dmi_check_system(pciprobe_dmi_table);

    when when have several peer root buses this could be called multiple
    times (which is bad), so move that call to pci_access_init().

    Signed-off-by: Yinghai Lu <yhlu.kernel@...il.com>
    Signed-off-by: Ingo Molnar <mingo@...e.hu>
    Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
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