* [kexec-lite PATCH V2] trampoline: Reset primary cpu endian to big-endian
@ 2015-07-08 3:29 Samuel Mendoza-Jonas
2015-07-08 3:37 ` Scott Wood
0 siblings, 1 reply; 5+ messages in thread
From: Samuel Mendoza-Jonas @ 2015-07-08 3:29 UTC (permalink / raw)
To: anton; +Cc: Samuel Mendoza-Jonas, linuxppc-dev
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.
Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
---
V2: As suggested by Anton take advantage of the rfid call and switch off
MSR_LE and branch to the target kernel in the same step.
kexec_trampoline.S | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/kexec_trampoline.S b/kexec_trampoline.S
index a3eb314..3751112 100644
--- a/kexec_trampoline.S
+++ b/kexec_trampoline.S
@@ -88,8 +88,15 @@ start:
li r5,0
- mtctr r4
- bctr
+ mtsrr0 r4
+
+ mfmsr r5
+ clrrdi r5,r5,1 /* Clear MSR_LE */
+ mtsrr1 r5
+
+ li r5,0
+
+ rfid
. = KERNEL_ADDR_OFFSET
kernel_addr:
--
2.4.5
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [kexec-lite PATCH V2] trampoline: Reset primary cpu endian to big-endian
2015-07-08 3:29 [kexec-lite PATCH V2] trampoline: Reset primary cpu endian to big-endian Samuel Mendoza-Jonas
@ 2015-07-08 3:37 ` Scott Wood
2015-07-08 3:49 ` Samuel Mendoza-Jonas
2015-07-08 10:10 ` Anton Blanchard
0 siblings, 2 replies; 5+ messages in thread
From: Scott Wood @ 2015-07-08 3:37 UTC (permalink / raw)
To: Samuel Mendoza-Jonas; +Cc: anton, linuxppc-dev
On Wed, 2015-07-08 at 13:29 +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.
>
> Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
> ---
> V2: As suggested by Anton take advantage of the rfid call and switch off
> MSR_LE and branch to the target kernel in the same step.
>
> kexec_trampoline.S | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/kexec_trampoline.S b/kexec_trampoline.S
> index a3eb314..3751112 100644
> --- a/kexec_trampoline.S
> +++ b/kexec_trampoline.S
> @@ -88,8 +88,15 @@ start:
>
> li r5,0
>
> - mtctr r4
> - bctr
> + mtsrr0 r4
> +
> + mfmsr r5
> + clrrdi r5,r5,1 /* Clear MSR_LE */
> + mtsrr1 r5
> +
> + li r5,0
> +
> + rfid
Is kexec-lite meant to be specific to book3s-64? The README just says "A
simple kexec for flattened device tree platforms" and I see a __powerpc64__
ifdef in kexec_trampoline.S (but not in the above patch)...
-Scott
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [kexec-lite PATCH V2] trampoline: Reset primary cpu endian to big-endian
2015-07-08 3:37 ` Scott Wood
@ 2015-07-08 3:49 ` Samuel Mendoza-Jonas
2015-10-06 22:40 ` Scott Wood
2015-07-08 10:10 ` Anton Blanchard
1 sibling, 1 reply; 5+ messages in thread
From: Samuel Mendoza-Jonas @ 2015-07-08 3:49 UTC (permalink / raw)
To: Scott Wood; +Cc: anton, linuxppc-dev
On 08/07/15 13:37, Scott Wood wrote:
> On Wed, 2015-07-08 at 13:29 +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.
>>
>> Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
>> ---
>> V2: As suggested by Anton take advantage of the rfid call and switch off
>> MSR_LE and branch to the target kernel in the same step.
>>
>> kexec_trampoline.S | 11 +++++++++--
>> 1 file changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/kexec_trampoline.S b/kexec_trampoline.S
>> index a3eb314..3751112 100644
>> --- a/kexec_trampoline.S
>> +++ b/kexec_trampoline.S
>> @@ -88,8 +88,15 @@ start:
>>
>> li r5,0
>>
>> - mtctr r4
>> - bctr
>> + mtsrr0 r4
>> +
>> + mfmsr r5
>> + clrrdi r5,r5,1 /* Clear MSR_LE */
>> + mtsrr1 r5
>> +
>> + li r5,0
>> +
>> + rfid
>
> Is kexec-lite meant to be specific to book3s-64? The README just says "A
> simple kexec for flattened device tree platforms" and I see a __powerpc64__
> ifdef in kexec_trampoline.S (but not in the above patch)...
>
> -Scott
>
I believe that particular ifdef is to check if we're little-endian when reading
the device tree, but that's still a good point - I'll check with Anton.
--
-----------
LTC Ozlabs
IBM
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [kexec-lite PATCH V2] trampoline: Reset primary cpu endian to big-endian
2015-07-08 3:49 ` Samuel Mendoza-Jonas
@ 2015-10-06 22:40 ` Scott Wood
0 siblings, 0 replies; 5+ messages in thread
From: Scott Wood @ 2015-10-06 22:40 UTC (permalink / raw)
To: sam.mj; +Cc: anton, linuxppc-dev
On Wed, 2015-07-08 at 13:49 +1000, Samuel Mendoza-Jonas wrote:
> On 08/07/15 13:37, Scott Wood wrote:
> > On Wed, 2015-07-08 at 13:29 +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.
> > >
> > > Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
> > > ---
> > > V2: As suggested by Anton take advantage of the rfid call and switch off
> > > MSR_LE and branch to the target kernel in the same step.
> > >
> > > kexec_trampoline.S | 11 +++++++++--
> > > 1 file changed, 9 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/kexec_trampoline.S b/kexec_trampoline.S
> > > index a3eb314..3751112 100644
> > > --- a/kexec_trampoline.S
> > > +++ b/kexec_trampoline.S
> > > @@ -88,8 +88,15 @@ start:
> > >
> > > li r5,0
> > >
> > > - mtctr r4
> > > - bctr
> > > + mtsrr0 r4
> > > +
> > > + mfmsr r5
> > > + clrrdi r5,r5,1 /* Clear MSR_LE */
> > > + mtsrr1 r5
> > > +
> > > + li r5,0
> > > +
> > > + rfid
> >
> > Is kexec-lite meant to be specific to book3s-64? The README just says "A
> > simple kexec for flattened device tree platforms" and I see a
> > __powerpc64__
> > ifdef in kexec_trampoline.S (but not in the above patch)...
> >
> > -Scott
> >
>
> I believe that particular ifdef is to check if we're little-endian when
> reading
> the device tree, but that's still a good point - I'll check with Anton.
It looks like this ended up going into main kexec, which means I get to find
some way to distinguish book3s from book3e to avoid that rfid. Yay.
-Scott
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [kexec-lite PATCH V2] trampoline: Reset primary cpu endian to big-endian
2015-07-08 3:37 ` Scott Wood
2015-07-08 3:49 ` Samuel Mendoza-Jonas
@ 2015-07-08 10:10 ` Anton Blanchard
1 sibling, 0 replies; 5+ messages in thread
From: Anton Blanchard @ 2015-07-08 10:10 UTC (permalink / raw)
To: Scott Wood; +Cc: Samuel Mendoza-Jonas, linuxppc-dev
Hi Scott,
> Is kexec-lite meant to be specific to book3s-64?
It was originally built to test book3s-64 kexec. Likely some other
issues need fixing for other ppc sub arches, but it is nice to
have a very simple kexec.
Anton
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2015-10-06 23:14 UTC | newest]
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2015-07-08 3:29 [kexec-lite PATCH V2] trampoline: Reset primary cpu endian to big-endian Samuel Mendoza-Jonas
2015-07-08 3:37 ` Scott Wood
2015-07-08 3:49 ` Samuel Mendoza-Jonas
2015-10-06 22:40 ` Scott Wood
2015-07-08 10:10 ` Anton Blanchard
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