Re: [PATCH] purgatory/arch/ppc64: Reset primary cpu endian to big-endian

Re: [PATCH] purgatory/arch/ppc64: Reset primary cpu endian to big-endian

[Simon Horman]

[CC linuxppc-dev]

On Fri, Aug 21, 2015 at 12:51:16PM +1000, Samuel Mendoza-Jonas wrote:
> Older big-endian ppc64 kernels don't include the FIXUP_ENDIAN check,
> meaning if we kexec from a little-endian kernel the target kernel will
> fail to boot.
> Returning to big-endian before we enter the target kernel ensures that
> the target kernel can boot whether or not it includes FIXUP_ENDIAN.
> 
> This mirrors commit 150b14e7 in kexec-lite.
> 
> Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>

I would value a review from one of the PPC folks.

> ---
>  purgatory/arch/ppc64/v2wrap.S | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/purgatory/arch/ppc64/v2wrap.S b/purgatory/arch/ppc64/v2wrap.S
> index dc5034f..179ade9 100644
> --- a/purgatory/arch/ppc64/v2wrap.S
> +++ b/purgatory/arch/ppc64/v2wrap.S
> @@ -114,10 +114,16 @@ master:
>  	LOADADDR(6,run_at_load) # the load flag
>  	lwz	7,0(6)		# possibly patched by kexec-elf-ppc64
>  	stw	7,0x5c(4)	# and patch it into the kernel
> -	li	5,0		# r5 will be 0 for kernel
> -	mtctr	4		# prepare branch too
>  	mr      3,16            # restore dt address
>  
> +	mtsrr0	4		# prepare branch to
> +
> +	mfmsr	5
> +	clrrdi	5,5,1		# clear MSR_LE
> +	mtsrr1	5
> +
> +	li	5,0		# r5 will be 0 for kernel
> +
>  				# skip cache flush, do we care?
>  
> -	bctr			# start kernel
> +	rfid			# update MSR and start kernel
> -- 
> 2.5.0
> 

Re: [PATCH] purgatory/arch/ppc64: Reset primary cpu endian to big-endian

[Michael Ellerman]

On Wed, 2015-09-02 at 10:02 +0900, Simon Horman wrote:
> [CC linuxppc-dev]
> 
> On Fri, Aug 21, 2015 at 12:51:16PM +1000, Samuel Mendoza-Jonas wrote:
> > Older big-endian ppc64 kernels don't include the FIXUP_ENDIAN check,
> > meaning if we kexec from a little-endian kernel the target kernel will
> > fail to boot.
> > Returning to big-endian before we enter the target kernel ensures that
> > the target kernel can boot whether or not it includes FIXUP_ENDIAN.
> > 
> > This mirrors commit 150b14e7 in kexec-lite.
> > 
> > Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
> 
> I would value a review from one of the PPC folks.

The diff looks good to me, and I've also tested it, so take your pick:

Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>

cheers

Re: [PATCH] purgatory/arch/ppc64: Reset primary cpu endian to big-endian

[Simon Horman]

On Thu, Sep 03, 2015 at 03:18:02PM +1000, Michael Ellerman wrote:
> On Wed, 2015-09-02 at 10:02 +0900, Simon Horman wrote:
> > [CC linuxppc-dev]
> > 
> > On Fri, Aug 21, 2015 at 12:51:16PM +1000, Samuel Mendoza-Jonas wrote:
> > > Older big-endian ppc64 kernels don't include the FIXUP_ENDIAN check,
> > > meaning if we kexec from a little-endian kernel the target kernel will
> > > fail to boot.
> > > Returning to big-endian before we enter the target kernel ensures that
> > > the target kernel can boot whether or not it includes FIXUP_ENDIAN.
> > > 
> > > This mirrors commit 150b14e7 in kexec-lite.
> > > 
> > > Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
> > 
> > I would value a review from one of the PPC folks.
> 
> The diff looks good to me, and I've also tested it, so take your pick:
> 
> Tested-by: Michael Ellerman <mpe@ellerman.id.au>
> Acked-by: Michael Ellerman <mpe@ellerman.id.au>

Thanks, I took the latter.

Re: [PATCH] purgatory/arch/ppc64: Reset primary cpu endian to big-endian

[Anton Blanchard]

Hi Horms,

> > Older big-endian ppc64 kernels don't include the FIXUP_ENDIAN check,
> > meaning if we kexec from a little-endian kernel the target kernel
> > will fail to boot.
> > Returning to big-endian before we enter the target kernel ensures
> > that the target kernel can boot whether or not it includes
> > FIXUP_ENDIAN.
> > 
> > This mirrors commit 150b14e7 in kexec-lite.
> > 
> > Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
> 
> I would value a review from one of the PPC folks.

Looks good to me. You can add:

Acked-by: Anton Blanchard <anton@samba.org>

Anton

> > ---
> >  purgatory/arch/ppc64/v2wrap.S | 12 +++++++++---
> >  1 file changed, 9 insertions(+), 3 deletions(-)
> > 
> > diff --git a/purgatory/arch/ppc64/v2wrap.S
> > b/purgatory/arch/ppc64/v2wrap.S index dc5034f..179ade9 100644
> > --- a/purgatory/arch/ppc64/v2wrap.S
> > +++ b/purgatory/arch/ppc64/v2wrap.S
> > @@ -114,10 +114,16 @@ master:
> >  	LOADADDR(6,run_at_load) # the load flag
> >  	lwz	7,0(6)		# possibly patched by
> > kexec-elf-ppc64 stw	7,0x5c(4)	# and patch it into the
> > kernel
> > -	li	5,0		# r5 will be 0 for kernel
> > -	mtctr	4		# prepare branch too
> >  	mr      3,16            # restore dt address
> >  
> > +	mtsrr0	4		# prepare branch to
> > +
> > +	mfmsr	5
> > +	clrrdi	5,5,1		# clear MSR_LE
> > +	mtsrr1	5
> > +
> > +	li	5,0		# r5 will be 0 for kernel
> > +
> >  				# skip cache flush, do we care?
> >  
> > -	bctr			# start kernel
> > +	rfid			# update MSR and start kernel
> > -- 
> > 2.5.0
> > 
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