[PATCH 1/2] powerpc: add Book E support to 64-bit hibernation

[Wang Dongsheng-B40534]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Friday, June 14, 2013 12:51 AM
> To: Wang Dongsheng-B40534
> Cc: Wood Scott-B07421; benh at kernel.crashing.org;
> johannes at sipsolutions.net; anton at enomsg.org; galak at kernel.crashing.org;
> linuxppc-dev at lists.ozlabs.org
> Subject: Re: [PATCH 1/2] powerpc: add Book E support to 64-bit
> hibernation
> 
> On 06/13/2013 04:55:43 AM, Wang Dongsheng-B40534 wrote:
> > > > +#else
> > > > +	/* Save SPRGs */
> > > > +	RESTORE_SPRG(0)
> > > > +	RESTORE_SPRG(1)
> > > > +	RESTORE_SPRG(2)
> > > > +	RESTORE_SPRG(3)
> > > > +	RESTORE_SPRG(4)
> > > > +	RESTORE_SPRG(5)
> > > > +	RESTORE_SPRG(6)
> > > > +	RESTORE_SPRG(7)
> > >
> > > Why do we need this on book3e and not on book3s?
> > >
> > Book3e: SPRG1 used save paca, SPRG2 be defined
> > SPRN_SPRG_TLB_EXFRAME,...
> > I think those register should be save, even now some SPRG register not
> > be use.
> 
> Are those expected/allowed to change as a result of the restore?
> 
Those registers are used by software, some allowed to change.
Exception handling is used in some registers, see exception-64e.h
These registers can be modified and saved.

> -Scott