Re: [OpenBIOS] [commit] r1043 - trunk/openbios-devel/arch/ppc/qemu

[Alexander Graf]

On 17.06.2011, at 21:51, Andreas Färber wrote:
> Am 17.06.2011 um 02:55 schrieb repository service:
> > Author: agraf
> > Date: Fri Jun 17 02:55:02 2011
> > New Revision: 1043
> > URL: http://tracker.coreboot.org/trac/openbios/changeset/1043
> >
> > Log:
> > ppc: fix mtmsr for SF setting
> >
> > When running openbios-ppc32 on a ppc64 VM, we need to unset SF on every
> > interrupt to ensure that things still work.
> >
> > So far we've been using mtmsr for this operation, but according to the
> > spec mtmsr doesn't set any bit above 32bit, so we were merely exploiting
> > a bug in qemu before.
> >
> > This patch adds a runtime check on MSR_SF to see if we're running on a 64-bit
> > capable CPU. If so, we use mtmsrd, which can set the high 32bits of MSR.
> >
> > CC: Andreas Färber 
> > CC: Segher Boessenkool 
> > Signed-off-by: Alexander Graf
> >
> > v1 -> v2:
> > use segher's awesome MSR_SF detection
> >
> > Modified:
> >  trunk/openbios-devel/arch/ppc/qemu/start.S
> > Modified: trunk/openbios-devel/arch/ppc/qemu/start.S
> >
> > --- trunk/openbios-devel/arch/ppc/qemu/start.S	Fri Jun 17 02:55:00 2011	(r1042)
> > +++ trunk/openbios-devel/arch/ppc/qemu/start.S	Fri Jun 17 02:55:02 2011	(r1043)
> > @@ -37,9 +37,16 @@
> >
> > #define EXCEPTION_PREAMBLE_TEMPLATE \
> >    mtsprg1	r1 ;				/* scratch */ \
> > mfcr	r1 ; \
> > mtsprg2	r1 ;				/* scratch */ \
> > lis	r1, 0x8000 ;			/* r1=0x80000000 */ \
> > add.	r1,r1,r1 ;			/* r1=r1+r1 (high 32bit !0) */ \
> > beq	1f; \
> > \
>
> This is more readable than the previous version, thanks.

Yeah, I prefer that version by a lot as well :).
> > mfmsr	r1 ;				/* unset MSR_SF */ \
> >    clrlwi	r1,r1,0 ; \
> > mtmsr	r1 ; \
> > mtmsrd	r1 ; \
> >
> > +1: \
> >    mfsprg0	r1 ;				/* exception stack in sprg0 */ \
> > .ifc ULONG_SIZE, 8 ; \
> >    addi	r1,r1,-(40 * ULONG_SIZE) ;	/* push exception frame */ \
> > @@ -85,7 +92,7 @@
> > \
> >    mflr	r0 ; \
> >    stl	r0,(13 * ULONG_SIZE)(r1) ; \
> > mfcr	r0 ; \
> > mfsprg2	r0 ; \
> > stl	r0,(14 * ULONG_SIZE)(r1) ; \
> > mfctr	r0 ; \
> > stl	r0,(15 * ULONG_SIZE)(r1) ; \
> >
> > @@ -301,14 +308,12 @@
> > ILLEGAL_VECTOR( 0x200 )
> >
> > VECTOR( 0x300, "DSI" ):
> > EXCEPTION_PREAMBLE
> > b	call_dsi_exception
> > b	real_dsi
> >
> > ILLEGAL_VECTOR( 0x380 )
> >
> > VECTOR( 0x400, "ISI" ):
> > EXCEPTION_PREAMBLE
> > b	call_isi_exception
> > b	real_isi
> >
> > ILLEGAL_VECTOR( 0x480 )
> >
> > @@ -359,6 +364,14 @@
> >
> > #endif
> >
> > +real_dsi:
> > EXCEPTION_PREAMBLE
> > b	call_dsi_exception
> >
> > +real_isi:
> > EXCEPTION_PREAMBLE
> > b	call_isi_exception
>
> I don't like the naming "real_xxx".

Feel free to just commit a patch that changes the naming.
> Have you checked that the serial output still has the same vector number (+4)?

Which serial output? This is really only here because the exception preamble became > 0x80 bytes.

Alex