[Qemu-devel] new entry in Qemu forum-- Andre Pech's fix on gdbstub

[Qemu-devel] new entry in Qemu forum-- Andre Pech's fix on gdbstub

[Mulyadi Santosa]

Hi...

I re-posted the patch by Andre Pech in Qemu forum. The URL is 
http://qemu.dad-answers.com/viewtopic.php?p=2809#2809

The patch is written to tackle missed breakpoint that sometimes happen. 
refer to the related Qemu forum's entry or the original Andre Pech's 
posting on December 24, 2005 in qemu-devel. I submitted this patch to 
Qemu forum on behalf of his name.

regards

Mulyadi

Re: [Qemu-devel] new entry in Qemu forum-- Andre Pech's fix on gdbstub

[Paul Brook]

On Monday 13 February 2006 05:06, Mulyadi Santosa wrote:
> Hi...
>
> I re-posted the patch by Andre Pech in Qemu forum. The URL is
> http://qemu.dad-answers.com/viewtopic.php?p=2809#2809
>
> The patch is written to tackle missed breakpoint that sometimes happen.
> refer to the related Qemu forum's entry or the original Andre Pech's
> posting on December 24, 2005 in qemu-devel. I submitted this patch to
> Qemu forum on behalf of his name.

This patch is not sufficient.

There seems to be some inconsistency whether cpu_get_phys_page_debug returns 
the physical address or the base address of the page.

Paul

Re: Re: [Qemu-devel] new entry in Qemu forum-- Andre Pech's fix on gdbstub

[Mulyadi Santosa]

Hi...

On Sunday 19 February 2006 22:39, Paul Brook wrote:
> This patch is not sufficient.
>
> There seems to be some inconsistency whether cpu_get_phys_page_debug
> returns the physical address or the base address of the page.

Hm, I am not so sure either. Anyway, using cscope to find out which 
functions that calls cpu_phys_page_debug, seems like it is only called 
during breakpoint setup. So, what ever we do inside 
cpu_get_phys_page_debug doesn't seem affecting other places.

BTW, do you have any suggestions on where should fix this problem?

regards

Mulyadi

Re: [Qemu-devel] new entry in Qemu forum-- Andre Pech's fix on gdbstub

[Paul Brook]

On Monday 20 February 2006 04:58, Mulyadi Santosa wrote:
> Hi...
>
> On Sunday 19 February 2006 22:39, Paul Brook wrote:
> > This patch is not sufficient.
> >
> > There seems to be some inconsistency whether cpu_get_phys_page_debug
> > returns the physical address or the base address of the page.
>
> Hm, I am not so sure either. Anyway, using cscope to find out which
> functions that calls cpu_phys_page_debug, seems like it is only called
> during breakpoint setup. So, what ever we do inside
> cpu_get_phys_page_debug doesn't seem affecting other places.

Ideally we'd fix the implementations of cpu_get_phys_page_debug so they are 
consistent. IIRC i386-softmmu and ppc-softmmu usually return the page base 
address, whereas everything else returns the actual address.
Typically the softmmu implementations use the same pagetable walking code as 
the normal tlb fault handling.

The quick and nasty solution is to make breakpoint_invalidate round the 
address to a page boundary before calling cpu_get_phys_page_debug, like 
cpu_memory_rw_debug does.

Paul