[OpenBIOS] [RFC 1/2] ppc: Set up SLBs for ppc64 (WIP)

[Andreas Färber]

Am 16.11.2010 um 00:41 schrieb Alexander Graf:

> On 16.11.2010, at 00:39, Andreas Färber wrote:
>
>> Set up SLBs with slbmte instead of mtsrin, suggested by Alex.
>> Adopt SLB example code from IBM application note.
>>
>> Cc: Alexander Graf <agraf at suse.de>
>> Signed-off-by: Andreas Färber <andreas.faerber at web.de>
>> ---
>> arch/ppc/qemu/ofmem.c |   35 ++++++++++++++++++++++++++++++++---
>> 1 files changed, 32 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/ppc/qemu/ofmem.c b/arch/ppc/qemu/ofmem.c
>> index e8b0b24..85b9956 100644
>> --- a/arch/ppc/qemu/ofmem.c
>> +++ b/arch/ppc/qemu/ofmem.c
>> @@ -393,7 +393,7 @@ void
>> setup_mmu( unsigned long ramsize )
>> {
>> 	ofmem_t *ofmem;
>> -	unsigned long sdr1, sr_base, msr;
>> +	unsigned long sdr1, msr;
>> 	unsigned long hash_base;
>> 	unsigned long hash_mask = 0xfff00000; /* alignment for ppc64 */
>> 	int i;
>> @@ -405,13 +405,42 @@ setup_mmu( unsigned long ramsize )
>> 	sdr1 = hash_base | ((HASH_SIZE-1) >> 16);
>> 	asm volatile("mtsdr1 %0" :: "r" (sdr1) );
>>
>> +#ifdef __powerpc64__
>> +#define SLB_SIZE 64
>> +#else
>> +#define SLB_SIZE 16
>> +#endif
>> +#if 1//def __powerpc64__
>> +#if 1
>> +    /* Initialize SLBs */
>> +    for (i = 0; i < SLB_SIZE; i++) {
>> +        unsigned long rs = (i << 12) | (0 << 7);
>> +        unsigned long rb = ((unsigned long)i << 28) | (0 << 27) | i;
>> +        asm volatile("slbmte %0,%1" :: "r" (rs), "r" (rb) :  
>> "memory");
>> +    }
>> +    /* Invalidate SLBs */
>> +    for (i = 1; i < SLB_SIZE; i++) {
>> +        unsigned long rb = ((unsigned long)i << 28) | (0 << 27);
>> +        asm volatile("slbie %0" :: "r" (rb) : "memory");
>> +    }
>> +#endif
>> +    /* Set SLBs */
>> +    for (i = 0; i < 16; i++) {
>> +        unsigned long rs = ((0x400 + i) << 12) | (0x10 << 7);
>> +        unsigned long rb = ((unsigned long)i << 28) | (1 << 27) | i;
>> +        asm volatile("slbmte %0,%1" :: "r" (rs), "r" (rb) :  
>> "memory");
>
> PPC32 doesn't have an SLB, only SRs :). So there you still need  
> mtsrin (or mtsr).

Thanks for the reminder. Can we agree then that OpenBIOS/ppc64 only  
needs to care about SLBs?
What I've been testing here though is that OpenBIOS/ppc on ppc64- 
softmmu doesn't break through my changes. And on ppc unsigned long is  
32 bits only. :)
Obviously needs cleanup, just an RFC.

I'd be interested to hear if this code that I ported is really  
necessary or correct (first setting them up so that they don't refer  
to the same *SID, then explicitly invalidate them and then set up the  
16 ones we care about for real.

Also, is SLB_SIZE 64 a universal number? This is from a document on  
the 970 MMU, and it's supposedly implementation-specific. Sounds scary.

Andreas