Re: [Qemu-devel] [PATCH] migration: Make analyze-migration script target-page-size aware

[Alexander Graf]

On 07.07.17 17:00, Dr. David Alan Gilbert wrote:
> * Alexander Graf (address@hidden) wrote:
> > The configuration section has a new subsection to transmit the target page
> > size along with the migration stream. The analyze migration script needs
> > to learn about that to read configuration streams that were triggering
> > this subsection to get transmitted.
> >
> > With this patch applied, I can successfully analyze migration streams
> > on AArch64 again.
> >
> > Signed-off-by: Alexander Graf <address@hidden>
> > ---
> >   scripts/analyze-migration.py | 13 +++++++++++++
> >   1 file changed, 13 insertions(+)
> >
> > diff --git a/scripts/analyze-migration.py b/scripts/analyze-migration.py
> > index 1455387..02784f2 100755
> > --- a/scripts/analyze-migration.py
> > +++ b/scripts/analyze-migration.py
> > @@ -254,12 +254,25 @@ class HTABSection(object):
>
> (Note I'm not a particularly python person, so take lightly)
>
> >   class ConfigurationSection(object):
> > +    QEMU_VM_SUBSECTION    = 0x05
> > +
>
> It's odd, you already have this constant defined twice in this script.

Yes, it lives once per class. I am not sure how to easily make it a global.

> >       def __init__(self, file):
> >           self.file = file
> >   
> >       def read(self):
> >           name_len = self.file.read32()
> >           name = self.file.readstr(len = name_len)
> > +        oldpos = self.file.tell()
> > +        if self.file.read8() == self.QEMU_VM_SUBSECTION:
> > +            name = self.file.readstr()
> > +            version_id = self.file.read32()
> > +            if name == "configuration/target-page-bits":
> > +                target_page_size = self.file.read32()
>
> All of your other references to target_page_size in the script
> are self.TARGET_PAGE_SIZE.

Well, all other ones are actual page sizes :). This variable is never 
used anywhere - we just want to stash it somewhere.

> You might want to make the conditional subsection check into a function
> somewhere, but that's OK for now.

I really hope we don't need it again. All subsections should be 
described via the in-stream json description. We just missed out the 
configuration one because it's not part of the object model.


Alex