Subject: Re: [PATCH 1/3] powerpc: bare minimum checkpoint/restart implementation

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 05 Feb 2009 07:58:19 +1100

On Wed, 2009-02-04 at 09:54 -0600, Serge E. Hallyn wrote:
> Quoting Benjamin Herrenschmidt ([email-masked]):
> > 
> > > +struct cr_hdr_cpu {
> > > +	struct pt_regs pt_regs;
> > > +	/* relevant fields from thread_struct */
> > > +	double fpr[32][TS_FPRWIDTH];
> > > +	unsigned int fpscr;
> > > +	int fpexc_mode;
> > > +	/* unsigned int align_ctl; this is never updated? */
> > > +	unsigned long dabr;
> > > +};
> > 
> > Is there some version or other identification somewhere ? If not there
> > should be. ie, we're going to add things here. For example, what about
> > the vector registers ? Also, some CPUs will have more HW debug registers
> > than just the DABR (we plan to add support for all the BookE architected
> > IACs and DACs for example), etc...
> 
> The arch-independent checkpoint header does have kernel
> maj:min:rev:patch info.  We expect to have to do more,
> assuming that the .config can change the arch-dependent
> cpu header (i.e. perhaps TS_FPRWIDTH could be changed).

It could to a certain extent... things like VSX, VSR, or freescale SPE,
or even the Cell SPU state etc....

I wonder if we want a tagged structure so we can easily add things...

Ben.