From: Len Brown <lenb@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
"Michael K. Johnson" <johnsonm@rpath.com>,
Justin Forbes <jmforbes@linuxtx.org>,
Jordan Hargrave <Jordan_Hargrave@dell.com>,
Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-acpi@vger.kernel.org
Subject: Re: [GIT PULL] x86 setup BIOS workarounds
Date: Thu, 02 Apr 2009 00:15:20 -0400 (EDT) [thread overview]
Message-ID: <alpine.LFD.2.00.0904012357050.4657@localhost.localdomain> (raw)
In-Reply-To: <200904011640.n31GeD0m008691@voreg.hos.anvin.org>
> + /* ACPI 3.0 added the extended flags support. If bit 0
> + in the extended flags is zero, we're supposed to simply
> + ignore the entry -- a backwards incompatible change! */
> + if (size > 20 && !(buf.ext_flags & 1))
> + continue;
At the risk of rushing to the defense of the ACPI spec...
This does not look like a backwards incompatible change to me.
In ACPI 2.0, size of 20 is always returned, and it would
be a Linux bug if we examined the undefined values after byte 19.
In ACPI 3.0, byte 20 is now defined. So if the BIOS returns
a size >= 21, we are permitted to examine byte 20.
So I agree with the test above, but I do not agree with the comment.
thanks,
Len Brown, Intel Open Source Technology Center
next parent reply other threads:[~2009-04-02 4:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200904011640.n31GeD0m008691@voreg.hos.anvin.org>
2009-04-02 4:15 ` Len Brown [this message]
2009-04-02 20:07 ` [GIT PULL] x86 setup BIOS workarounds H. Peter Anvin
[not found] ` <alpine.LFD.2.00.0904011115210.4130@localhost.localdomain>
2009-04-02 4:26 ` Len Brown
2009-04-02 19:31 ` Linus Torvalds
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