Re: [Qemu-devel] softmmu thoughts

[Piotras <piotras@gmail.com>]

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Hi!

I updated the patch to solve problems reported by Jens Arm:
  * compilation problem on Mandrake 9.1
  * SEGV problem when working with non-TLS glibc.
Jens, thanks for your help!

I also cleaned-up the code and comments in several places (for 
example page_unprotect).

The patch should apply cleanly to recent CVS. It should work 
with 0.6.1 without problems too.


Regards,

Piotrek

On Tue, 14 Dec 2004 18:54:04 +0100, Piotras <piotras@gmail.com> wrote:
> Hi!
> 
> I'm attaching a new patch based on your suggestions. On my machine
> nbench gives:
>     memory index: 37% up
>     integer index: 36% up
>     fp index: 4% up
> 
> The patch is divided in three files to simplify review. Part 1 contains
> mostly rearrangement existing code necessary for the patch. Part 2
> adds the new mmu mode. Part 3 contains heuristic to optimize
> performance of iomem and self modifying code.
> 
> To test the patch create a build directory and run:
>  > tar -zxf _PATH_TO_qemu-0.6.1.tar.gz
>  > tar -zxf _PATH_TO_linux-test-0.5.1.tar.gz
>  > cd qemu-0.6.1
>  > ./configure --target-list=i386-softmmu
>  > gunzip < _PATH_TO_mmu-part1.patch.gz | patch -p1
>  > gunzip < _PATH_TO_mmu-part2.patch.gz | patch -p1
>  > gunzip < _PATH_TO_mmu-part3.patch.gz | patch -p1
>  > make
>  > ./i386-softmmu/qemu -m 64 -L pc-bios -hda ../linux-test/linux.img
> 
> Last but not least. I'd like to acknowledge Magnus contribution -- VM
> setup code is derived from his work.
> 
> Regards,
> 
> Piotrek
> 
> On Wed, 20 Oct 2004 14:41:42 +0200, Fabrice Bellard <fabrice@bellard.org> wrote:
> > Hi,
> >
> > The idea is interesting. Here are several suggestions:
> >
> > - It would be more efficient and simpler to map one 4KB host memory page
> > every 8 KB. Then you can have a fixed mmap() mapping (no syscall
> > overhead to change the mappings) and a simple way to handle unaligned
> > accesses.
> > - The critical point would be to keep standard soft MMU accesses for
> > device access. An architectural change is needed to do that, but it
> > seems easy to add.
> > - This patch should work with qemu, not qemu-fast. The future of
> > qemu-fast is to use a kernel module to have near native performances. It
> > is not worthwhile to invest time in soft MMU or dynamic translation when
> > you can just execute the code as is !
> >
> > Fabrice.

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