[Qemu-devel] Thanks for QEMU!

[Qemu-devel] Thanks for QEMU!

[John Stracke]

Just wanted to send a thank-you for developing QEMU.  I'm writing an OS
for my master's thesis, and having an open-source emulation of the CPU
has been a *huge* help.  At least three times now, there's been some
subtlety that I couldn't figure out from the CPU docs, so I adding some
printf()s to QEMU to figure out what was really going on.

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|Francois Thibault   |==========================================|
|East Kingdom        |"The struggle is always worthwhile, if the|
|francis@thibault.org|end be worthwhile and the means honorable;|
|                    |foreknowledge of defeat is not sufficient |
|                    |reason to withdraw from the contest." --  |
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Re: [Qemu-devel] Thanks for QEMU!

[Hetz Ben Hamo]

Hi,

On 11/7/06, John Stracke <francis+dated+1178460433.897649@thibault.org> wrote:
> Just wanted to send a thank-you for developing QEMU.  I'm writing an OS
> for my master's thesis, and having an open-source emulation of the CPU
> has been a *huge* help.  At least three times now, there's been some
> subtlety that I couldn't figure out from the CPU docs, so I adding some
> printf()s to QEMU to figure out what was really going on.

Perhaps you could submit your printf's so other people can learn from
them please?

Thanks,
Hetz

Re: [Qemu-devel] Thanks for QEMU!

[wangji]

francis,
why not leave your development_available as readonly_access (svn_like or 
anyftp) it would be great for learning !
(to complement wikipedia_microkernel !!! )

 just to recall on linux_kernel stuff

1998 Bowman effort's reverse eng
concrete (as-built) architecture of the Linux kernel : (1998)
http://plg.uwaterloo.ca/~itbowman/CS746G/a2   
2005 zhao Jiong reconstruct's linux-011 
http://linux.inet.hr/ols2005_adopting_and_commenting_the_old_kernel_source_code_for_education.html
http://www.quinnli.com/upload/linux-0.11.swf
>Khi Thứ ba  07 Tháng mười một 2006 4:09 chiều, John Stracke viết:
> Just wanted to send a thank-you for developing QEMU.  I'm writing an OS
> for my master's thesis, and having an open-source emulation of the CPU
> has been a *huge* help.  At least three times now, there's been some
> subtlety that I couldn't figure out from the CPU docs, so I adding some
> printf()s to QEMU to figure out what was really going on.

Re: [Qemu-devel] Thanks for QEMU!

[John Stracke]

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On Wed, 2006-11-08 at 14:31 +0100, wangji wrote:

> francis,
> why not leave your development_available as readonly_access (svn_like or=20
> anyftp) it would be great for learning !


I probably will release it once I finish my thesis.  However, at
present, it's not in good shape to be built by other people.

-- 
/============================================================\
|John Stracke        | http://www.thibault.org |HTML OK      |
|Francois Thibault   |=======================================|
|East Kingdom        |"The Reality Check's in the mail." --L.|
|francis@thibault.org|Peter Deutsch                          |
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Re: [Qemu-devel] Thanks for QEMU!

[John Stracke]

Hetz Ben Hamo wrote:


> Perhaps you could submit your printf's so other people can learn from
> them please?

Well, most of them I no longer have; they slowed things down, so I
deleted them once I had the problems fixed.  Besides, they were probably
too idiosyncratic to help other people much.

However, there is one change that I'd recommend adding into the QEMU
distribution: in target-i386/helper2.c, in cpu_x86_handle_mmu_fault(),
right before the line starting "pde_addr = ((env->cr[3] & ~0xfff)", I
added a sanity check:

if (env->cr[3] & 0xfff) {
  fprintf(logfile,"Warning: page directory is not page-aligned.\n");
}

This gives a warning if the OS is using an invalid address for the page
directory.  You might want to put it inside #ifdef DEBUG_MMU, or
something.

-- 
/============================================================\
|John Stracke        | http://www.thibault.org |HTML OK      |
|Francois Thibault   |=======================================|
|East Kingdom        |Rope is rope, and string is string, and|
|francis@thibault.org|never the twine shall meet.            |
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