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Re: [Qemu-devel] Commit b2a575a1c652 broke i486 support.
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From: |
Richard W.M. Jones |
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Subject: |
Re: [Qemu-devel] Commit b2a575a1c652 broke i486 support. |
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Date: |
Wed, 31 May 2017 10:03:22 +0100 |
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User-agent: |
Mutt/1.5.20 (2009-12-10) |
On Tue, May 30, 2017 at 02:05:15PM -0500, Rob Landley wrote:
> On 05/29/2017 05:14 AM, Richard W.M. Jones wrote:
> > I see in the disassembly use of cmovne (new in Pentium Pro) and
> > bswap (new in 486).
> > [http://cse.unl.edu/~goddard/Courses/CSCE351/IntelArchitecture/InstructionSetSummary.pdf]
> >
> > The cmovne instruction is generated by the compiler (GCC in my case),
> >
> > The following patch removes the cmovne instruction, so it should work
> > on 486 (although I didn't test it). It's not possible to remove bswap
> > without surgery on the inline assembler.
>
> Is there any way to make it just _not_ load the option rom for -cpu 486?
> It ran fine before that thing went in...
Well it ran, but it was very slow. The DMA method can be literally
orders of magnitude faster.
Does adding the flag I suggested help?
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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