[OpenBIOS] [PATCH] ppc: use rfid when running under a CPU from the 970 family.

[Mark Cave-Ayland]

On 20/06/16 10:33, Alexander Graf wrote:

> On 06/20/2016 11:32 AM, Cédric Le Goater wrote:
>> On 06/20/2016 09:39 AM, Alexander Graf wrote:
>>>
>>> On 20.06.16 09:34, Cédric Le Goater wrote:
>>>> A recent attempt to restrict the use of rfi to 64bit cpus in qemu
>>>> broke 32bit OpenBIOS when run under a 970.
>>>>
>>>> This is adding a dynamic check on the pvr to choose between rfi and
>>>> rfid. Only the 970 family is supported.
>>>>
>>>> Signed-off-by: Cédric Le Goater <clg at kaod.org>
>>>> ---
>>>>
>>>>   Tested on qemu.
>>>>
>>>>   arch/ppc/qemu/start.S |   25 +++++++++++++++++++++++--
>>>>   arch/ppc/start.S      |   25 +++++++++++++++++++++++--
>>>>   2 files changed, 46 insertions(+), 4 deletions(-)
>>>>
>>>> Index: openbios.git/arch/ppc/qemu/start.S
>>>> ===================================================================
>>>> --- openbios.git.orig/arch/ppc/qemu/start.S
>>>> +++ openbios.git/arch/ppc/qemu/start.S
>>>> @@ -27,6 +27,27 @@
>>>>     #ifdef CONFIG_PPC_64BITSUPPORT
>>>>   +/* When running on ppc64, we cannot use rfi anymore. Let's try to
>>>> + * catch which cpu we are running on and act accordingly. This is
>>>> + * for 970s only.
>>> Do you think you could move the check into the cpu init function and use
>>> a global variable / live patching instead? I don't remember if we need
>>> to handle any faults before we reach that path.
>> So we get an ISI really early, when returning from setup_mmu(), which is
>> the first call in _entry.
> 
> Ok, can we add the check there?

Bear in mind that the code for entry/context switching has been reworked
pending commit whilst we switch the OpenBIOS repository over from SVN to
git. The relevant commits are here:
https://www.coreboot.org/pipermail/openbios/2016-May/009395.html.

So please consider OpenBIOS git master plus the patchset above to be the
latest code.

Jeff/Stefan - completing the migration is becoming increasing important
now, any news on an ETA?


ATB,

Mark.