From: Kevin O'Connor <kevin@koconnor.net>
To: Michael Brown <mbrown@fensystems.co.uk>
Cc: ipxe-devel@lists.ipxe.org,
"seabios@seabios.org" <seabios@seabios.org>,
Avi Kivity <avi@redhat.com>, KVM list <kvm@vger.kernel.org>,
qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [ipxe-devel] Big real mode use in ipxe
Date: Sun, 19 Aug 2012 11:53:32 -0400 [thread overview]
Message-ID: <20120819155332.GC12794@morn.localdomain> (raw)
In-Reply-To: <201208191634.50590.mbrown@fensystems.co.uk>
On Sun, Aug 19, 2012 at 04:34:50PM +0100, Michael Brown wrote:
> On Sunday 19 Aug 2012 16:07:05 Avi Kivity wrote:
> > (and that seabios needs changes to either work in
> > big real mode, or to put the processor back into big real mode after
> > returning from a PMM service.
>
> If seabios switches into protected mode when performing a PMM service, then it
> _must_ leave the segment limits at 4G when returning to real mode. To do
> otherwise will violate the PMM spec, and will break conforming clients such as
> iPXE.
SeaBIOS does switch to 32bit mode during PMM calls and does switch to
16bit "big real" mode (segment limits set to 4G) on return.
-Kevin
next prev parent reply other threads:[~2012-08-19 15:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-19 15:07 [Qemu-devel] Big real mode use in ipxe Avi Kivity
2012-08-19 15:34 ` [Qemu-devel] [ipxe-devel] " Michael Brown
2012-08-19 15:42 ` Avi Kivity
2012-08-19 15:53 ` Kevin O'Connor [this message]
2012-08-19 15:44 ` [Qemu-devel] " Kevin O'Connor
2012-08-19 15:52 ` Avi Kivity
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