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

[Blue Swirl <blauwirbel@gmail.com>]

On Sun, Jan 24, 2010 at 2:02 AM, Artyom Tarasenko
<atar4qemu@googlemail.com> 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 should use
st[bwlq]_phys_notdirty. It can break display handling, though.