Re: [Xen-devel] pygrub patch to allow explicit offset to fs

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-06-19 at 09:39 +0100, Wei Liu wrote:
> On Wed, Jun 19, 2013 at 09:17:30AM +0100, Ian Campbell wrote:
> > On Wed, 2013-06-19 at 01:40 +0200, Kjetil Torgrim Homme wrote:
> > > I recently needed an old VM to work even though it was created on a SAN 
> > > LUN with no partition table, just LVM straight onto the raw device.
> > > 
> > > pygrub didn't like this, so I added a simple hack to allow the user to 
> > > override pygrub's probing when necessary.  please consider applying this 
> > > patch.  btw, I think most LVM will have first filesystem at offset 196608.
> > > 
> > > 
> > > commit 80a3f7b48da235695f8560deb41c19b23e7799e3
> > > Author: Kjetil Torgrim Homme <kjetil.homme@xxxxxxxxxxxxxxxxxx>
> > > Date:   Wed Jun 19 00:54:43 2013 +0200
> > > 
> > >      allow user to specify offset parameter which overrides partition 
> > > table parsing
> > > 
> > >      Signed-off-by: Kjetil Torgrim Homme <kjetil.homme@xxxxxxxxxxxxxxxxxx>
> > 
> > Looks good to me, thanks.
> > 
> > Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > 
> > although I've suggested a possible simplification below.
> > 
> > I think with the freeze being in force this, as a new feature, will have
> > to wait for the 4.4 dev cycle to be applied, although I will defer to
> > George's judgement.
> > 
> > > diff --git a/tools/pygrub/src/pygrub b/tools/pygrub/src/pygrub
> > > index eedfdb2..d46ee8c 100644
> > > --- a/tools/pygrub/src/pygrub
> > > +++ b/tools/pygrub/src/pygrub
> > > [...]
> > > @@ -765,6 +765,7 @@ if __name__ == "__main__":
> > >      interactive = True
> > >      list_entries = False
> > >      isconfig = False
> > > +    user_provided_offset = None
> > 
> > If you make this "part_offs = None"...
> > 
> > >      debug = False
> > >      not_really = False
> > >      output_format = "sxp"
> > > @@ -797,6 +798,8 @@ if __name__ == "__main__":
> > >              incfg["ramdisk"] = a
> > >          elif o in ("--args",):
> > >              incfg["args"] = a
> > > +        elif o in ("--offset",):
> > > +            user_provided_offset = a
> > 
> > ... and this "part_offs = int(a)" ... (or [int(a)] if that's correct)
> 
> Need to take care of exception in this conversion.

Yes, and the original had this problem too now you mention it.

> > >          elif o in ("--entry",):
> > >              entry = a
> > >              # specifying the entry to boot implies non-interactive
> > > @@ -840,7 +843,10 @@ if __name__ == "__main__":
> > >          bootfsoptions = ""
> > >  
> > >      # get list of offsets into file which start partitions
> > > -    part_offs = get_partition_offsets(file)
> > > +    if user_provided_offset is None:
> > > +        part_offs = get_partition_offsets(file)
> > > +    else:
> > > +        part_offs = [ int(user_provided_offset) ]
> > 
> > Then this can become just:
> >      if part_offs = None:
> 
> You do know you missed a "=" here, right? :-)

I claim pseudo-code ;-)

> 
> 
> Wei.
> 
> >          part_offs = get_partition_offsets(file)
> > > 
> > > Ian.
> > 
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-devel



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