Re: [Xen-devel] [PATCH] VM generation ID save/restore and migrate

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Ian Jackson [mailto:Ian.Jackson@xxxxxxxxxxxxx]
> Sent: 13 December 2011 15:45
> To: Paul Durrant
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH] VM generation ID save/restore and
> migrate
> 
> Paul Durrant writes ("[Xen-devel] [PATCH] VM generation ID
> save/restore and migrate"):
> > VM generation ID save/restore and migrate.
> >
> > Add code to track the address of the VM generation id buffer
> across a
> > save/restore or migrate and increment it as necessary.
> > The address of the buffer is written into xenstore by hvmloader at
> > boot time. It must be read from xenstore by the caller of
> > xc_domain_save() and then written back again by the caller of
> > xc_domain_restore().
> ...
> > +        if ( RDEXACT(fd, &buf->vm_gid_addr, sizeof(uint32_t)) ||
> > +             RDEXACT(fd, &buf->vm_gid_addr, sizeof(uint64_t)) )
> 
> I'm generally OK with this, but I have two comments.  Firstly
> "vm_gid_addr" etc. is a bit opaque and there might be lots of things
> called a "g identifier".
> 
> Perhaps we could call these variables
>   vm_generationid_addr
> or something ?
> 

If you're happy that's not too long, I'll go with that.

> > +    ents[12] = "data/generation-id";
> 
> And this xenstore key suggests that the value is the id, not the
> address.  I think it should be renamed.
> 

Ok. I'll need to patch hvmloader again then. I'll prepend a patch this one to 
change the name.

  Paul

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