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Re: [Qemu-devel] [PATCH] migration: Make analyze-migration script target
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH] migration: Make analyze-migration script target-page-size aware |
Date: |
Mon, 10 Jul 2017 12:53:47 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
* Alexander Graf (address@hidden) wrote:
>
>
> 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.
Well you do read self.TARGET_PAGE_SIZE elsewhere - it determines the
amount of data to read from each RAM header in RamSections::read
Also note that the value being read in the config header is
target_page_bits - i.e. ln2(target_page_size).
> > 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.
Dave
>
> Alex
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK