Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI" - Kernel

This is a discussion on Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI" - Kernel ; Matthew Garrett wrote: > On Fri, Nov 07, 2008 at 09:01:19AM +0800, Zhao Yakui wrote: > >> With the help of KVM I find that the windows will be rebooted by writing >> RESET_VALUE to RESET_REG I/O port if the ...

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Thread: Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI"

  1. Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI"

    Matthew Garrett wrote:
    > On Fri, Nov 07, 2008 at 09:01:19AM +0800, Zhao Yakui wrote:
    >
    >> With the help of KVM I find that the windows will be rebooted by writing
    >> RESET_VALUE to RESET_REG I/O port if the RESET_REG_SUP bit is not
    >> zero(It indicates whether ACPI reboot is supported).
    >> IMO maybe the ACPI reboot is the first choice. If it can't, then it will
    >> fall back to other mode.

    >
    > Hmm. But we're seeing some machines that end up very confused if
    > rebooted via ACPI. I guess we need to run Vista on them to find out how
    > they behave. What OSI strings did your KVM setup expose? We know that
    > Windows changes behaviour under various circumstances depending on which
    > OS the firmware requests, so it's almost possible that this is another
    > of those cases.


    Given that Windows behavior, this patch seems suspicious:

    http://git.kernel.org/?p=linux/kerne...62c20576238f5a

    This patch ignores the RESET_REG_SUP flag and just tries using the reset
    register anyway if it thinks it's valid. So we may attempt ACPI reset on
    machines which don't indicate it's supported.

    The patch description mentioned that some machines didn't reboot after
    S3 suspend without this patch. However, we recently had this patch merged:

    http://git.kernel.org/?p=linux/kerne...13a5b4f99a6888

    Is it possible that the problem fixed there is the true cause of this
    reboot after S3 problem?
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  2. Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI"

    On Thu, Nov 06, 2008 at 07:30:43PM -0600, Robert Han**** wrote:

    > http://git.kernel.org/?p=linux/kerne...62c20576238f5a
    >
    > This patch ignores the RESET_REG_SUP flag and just tries using the reset
    > register anyway if it thinks it's valid. So we may attempt ACPI reset on
    > machines which don't indicate it's supported.


    Yeah, that sounds very wrong.

    > The patch description mentioned that some machines didn't reboot after
    > S3 suspend without this patch. However, we recently had this patch merged:
    >
    > http://git.kernel.org/?p=linux/kerne...13a5b4f99a6888
    >
    > Is it possible that the problem fixed there is the true cause of this
    > reboot after S3 problem?


    Oh, yeah, could be. Given the From:, I should really have thought of
    that

    --
    Matthew Garrett | mjg59@srcf.ucam.org
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  3. Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI"



    On Fri, 7 Nov 2008, Matthew Garrett wrote:

    > On Thu, Nov 06, 2008 at 07:30:43PM -0600, Robert Han**** wrote:
    >
    > > http://git.kernel.org/?p=linux/kerne...62c20576238f5a
    > >
    > > This patch ignores the RESET_REG_SUP flag and just tries using the reset
    > > register anyway if it thinks it's valid. So we may attempt ACPI reset on
    > > machines which don't indicate it's supported.

    >
    > Yeah, that sounds very wrong.


    As it turns out, it was an incorrect guess on our part on how to be "bug
    compatible" and I'm reverting it per the regression report here:

    http://bugzilla.kernel.org/show_bug.cgi?id=11942

    -Len

    > > The patch description mentioned that some machines didn't reboot after
    > > S3 suspend without this patch. However, we recently had this patch merged:
    > >
    > > http://git.kernel.org/?p=linux/kerne...13a5b4f99a6888
    > >
    > > Is it possible that the problem fixed there is the true cause of this
    > > reboot after S3 problem?

    >
    > Oh, yeah, could be. Given the From:, I should really have thought of
    > that
    >
    > --
    > Matthew Garrett | mjg59@srcf.ucam.org
    >

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  4. Re: [PATCH 15/15] Revert "x86: default to reboot via ACPI"

    On Friday, 7 of November 2008, Robert Han**** wrote:
    > Matthew Garrett wrote:
    > > On Fri, Nov 07, 2008 at 09:01:19AM +0800, Zhao Yakui wrote:
    > >
    > >> With the help of KVM I find that the windows will be rebooted by writing
    > >> RESET_VALUE to RESET_REG I/O port if the RESET_REG_SUP bit is not
    > >> zero(It indicates whether ACPI reboot is supported).
    > >> IMO maybe the ACPI reboot is the first choice. If it can't, then it will
    > >> fall back to other mode.

    > >
    > > Hmm. But we're seeing some machines that end up very confused if
    > > rebooted via ACPI. I guess we need to run Vista on them to find out how
    > > they behave. What OSI strings did your KVM setup expose? We know that
    > > Windows changes behaviour under various circumstances depending on which
    > > OS the firmware requests, so it's almost possible that this is another
    > > of those cases.

    >
    > Given that Windows behavior, this patch seems suspicious:
    >
    > http://git.kernel.org/?p=linux/kerne...62c20576238f5a
    >
    > This patch ignores the RESET_REG_SUP flag and just tries using the reset
    > register anyway if it thinks it's valid. So we may attempt ACPI reset on
    > machines which don't indicate it's supported.
    >
    > The patch description mentioned that some machines didn't reboot after
    > S3 suspend without this patch. However, we recently had this patch merged:
    >
    > http://git.kernel.org/?p=linux/kerne...13a5b4f99a6888
    >
    > Is it possible that the problem fixed there is the true cause of this
    > reboot after S3 problem?


    Generally, it is.

    Should it regarded as -stable material, BTW, or is it already in -stable?

    Matthew?

    Thanks,
    Rafael
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