[Qemu-devel] Re: sparc solaris guest, hsfs_putpage: dirty HSFS page

[Artyom Tarasenko]

2010/1/26 Blue Swirl <address@hidden>:
> On Tue, Jan 26, 2010 at 7:03 PM, Artyom Tarasenko
> <address@hidden> wrote:
>> 2010/1/24 Blue Swirl <address@hidden>:
>>> On Sun, Jan 24, 2010 at 2:02 AM, Artyom Tarasenko
>>> <address@hidden> wrote:
>>>> All solaris versions which currently boot (from cd) regularly produce 
>>>> buckets of
>>>> "hsfs_putpage: dirty HSFS page" messages.
>>>>
>>>> High Sierra is a pretty old and stable stuff, so it is possible that
>>>> the code is similar to OpenSolaris.
>>>> I looked in debugger, and the function calls hierarchy looks pretty 
>>>> similar.
>>>>
>>>> Now in the OpenSolaris source code there is a nice comment:
>>>> http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/fs/hsfs/hsfs_vnops.c#1758
>>>> /*
>>>> * Normally pvn_getdirty() should return 0, which
>>>> * impies that it has done the job for us.
>>>> * The shouldn't-happen scenario is when it returns 1.
>>>> * This means that the page has been modified and
>>>> * needs to be put back.
>>>> * Since we can't write on a CD, we fake a failed
>>>> * I/O and force pvn_write_done() to destroy the page.
>>>> */
>>>> if (pvn_getdirty(pp, flags) == 1) {
>>>>                cmn_err(CE_NOTE,
>>>>                            "hsfs_putpage: dirty HSFS page");
>>>>
>>>> Now the question: does the problem have to do with qemu caches 
>>>> (non-)emulation?
>>>> Can it be that we mark non-dirty pages dirty? Or does qemu always mark
>>>> pages dirty exactly to avoid cache emulation?
>>>>
>>>> Otherwise it means something else goes astray and Solaris guest really
>>>> modifies the pages it shouldn't.
>>>>
>>>> Just wonder what to dig first, MMU or IRQ emulation (the two most
>>>> obvious suspects).
>>>
>>> Maybe the stores via MMU bypass ASIs
>>
>> why bypass stores? What about the non-bypass ones?
>
> Because their use should update the PTE dirty bits.

update !=always set. Where is it implemented? I guess the code is
shared between multiple architectures.
Is there a way to trace at what point certain page is getting dirty?

Since it's not the bypass ASIs it must be something else.

>>> should use
>>> st[bwlq]_phys_notdirty.
>>
>> Seems that st[bw]_phys_notdirty are not implemeted yet?
>>
>> I've changed [lq] for asi 0x20 and 21-2f and see no difference. Also I
>> put some debug printfs and see that none of these ASIs is called after
>> the Solaris kernel is loaded.


-- 
Regards,
Artyom Tarasenko

solaris/sparc under qemu blog: http://tyom.blogspot.com/