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From: Ingo Molnar <mingo@elte.hu>
To: Zachary Amsden <zach@vmware.com>
Cc: Andrew Morton <akpm@osdl.org>, Chris Wright <chrisw@osdl.org>,
	Linus Torvalds <torvalds@osdl.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Virtualization Mailing List <virtualization@lists.osdl.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Zwane Mwaikambo <zwane@arm.linux.org.uk>,
	Martin Bligh <mbligh@mbligh.org>,
	Pratap Subrahmanyam <pratap@vmware.com>,
	Christopher Li <chrisl@vmware.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH 4/21] i386 Broken bios common
Date: Tue, 8 Nov 2005 13:57:09 +0100	[thread overview]
Message-ID: <20051108125709.GA4218@elte.hu> (raw)
In-Reply-To: <43709E86.8010203@vmware.com>


* Zachary Amsden <zach@vmware.com> wrote:

> >>-	gdt[0x40 / 8] = bad_bios_desc;
> >>+	gdt[0x40 / 8] = gdt[GDT_ENTRY_BAD_BIOS_CACHE];
> >
> >i like the cleanup, but wouldnt it be simpler to dedicate GDT entry #8 
> >to the 0x40 descriptor, and hence be compatible with such broken BIOSes 
> >by default? Right now entry #8 is taken up by TLS segment #2, but we 
> >could change GDT_ENTRY_TLS_MIN from 6 to 9 and push the TLS segments to 
> >entries 9,10,11. [ Could there be any buggy SMM code that relies on 
> >having something at 0x40? ]
> 
> I worry that there could be buggy userspace code that relies on having 
> selector 0x40 - notably Wine.  So although I would like to make 0x40 
> the default, can't be guaranteed.

why use up a GDT entry then for GDT_ENTRY_BAD_BIOS_CACHE? Just put it 
into a global variable, into the readmostly section.

	Ingo

  reply	other threads:[~2005-11-08 12:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-11-08  4:22 Zachary Amsden
2005-11-08  7:19 ` Ingo Molnar
2005-11-08 12:48   ` Zachary Amsden
2005-11-08 12:57     ` Ingo Molnar [this message]
2005-11-08 15:06 ` Linus Torvalds
2005-11-08 15:16   ` H. Peter Anvin
2005-11-08 21:07   ` Zachary Amsden
2005-11-08 21:52   ` Zachary Amsden

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