On Tue, Feb 2, 2010 at 3:01 PM, Ralf Baechle <ralf@xxxxxxxxxxxxxx> wrote:
> On Tue, Feb 02, 2010 at 02:37:41AM -0800, Guenter Roeck wrote:
>
> Pretty good, let the nitpicking start :-)
I haven't been following this closely enough, so maybe my question is
stupid. However: will this work on SGI R5000? I'm using an Indy, so
I'm quite concerned about this CPU.
Thanks,
Dmitri
>
>> diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
>> index 1f4df64..284eb55 100644
>> --- a/arch/mips/include/asm/cpu-features.h
>> +++ b/arch/mips/include/asm/cpu-features.h
>> @@ -209,6 +209,9 @@
>> # ifndef cpu_has_64bit_addresses
>> # define cpu_has_64bit_addresses 1
>> # endif
>> +# ifndef cpu_vmbits
>> +# define cpu_vmbits cpu_data[0].vmbits
>> +# endif
>> #endif
>
> For 32-bit kernels we probably should fix cpu_vmbits to 31.
>
> #ifdef CONFIG_64BIT
> # ifndef cpu_vmbits
> # define cpu_vmbits cpu_data[0].vmbits
> # define __NEED_VMBITS
> # endif
> #else
> # #define cpu_vmbits 31
> #endif
>
>> #if defined(CONFIG_CPU_MIPSR2_IRQ_VI) && !defined(cpu_has_vint)
>> diff --git a/arch/mips/include/asm/cpu-info.h b/arch/mips/include/asm/cpu-info.h
>> index 1260443..3c694bc 100644
>> --- a/arch/mips/include/asm/cpu-info.h
>> +++ b/arch/mips/include/asm/cpu-info.h
>> @@ -58,6 +58,7 @@ struct cpuinfo_mips {
>> struct cache_desc tcache; /* Tertiary/split secondary cache */
>> int srsets; /* Shadow register sets */
>> int core; /* physical core number */
>> + int vmbits; /* Virtual memory size in bits */
>
> #ifdef __NEED_VMBITS
> int vmbits; /* Virtual memory size in bits */
> #endif
>
> To do for a later separate patch - minimize the sizes of all cpuinfo_mips
> members; int is overkill for many members.
>
>> #if defined(CONFIG_MIPS_MT_SMP) || defined(CONFIG_MIPS_MT_SMTC)
>> /*
>> * In the MIPS MT "SMTC" model, each TC is considered
>> diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h
>> index 9cd5089..8eda30b 100644
>> --- a/arch/mips/include/asm/pgtable-64.h
>> +++ b/arch/mips/include/asm/pgtable-64.h
>> @@ -110,7 +110,9 @@
>> #define VMALLOC_START MAP_BASE
>> #define VMALLOC_END \
>> (VMALLOC_START + \
>> - PTRS_PER_PGD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE - (1UL << 32))
>> + min(PTRS_PER_PGD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE, \
>> + (1UL << cpu_vmbits)) - (1UL << 32))
>> +
>
> This overlaps with other allocations near the top - yes, we've been living
> dangerous but with bottom up allocations a conflict was very, very unlikely.
>
> Dealing with them in a sane way in the VMALLOC_END macro definition is hard,
> so I suggest changing the definition to something like:
>
> extern unsigned long vmalloc_end;
>
> #define VMALLOC_START MAP_BASE
> #define VMALLOC_END vmalloc_end
>
> And initialize the value of vmalloc_end in something like the mm section of
> arch/mips/kernel/traps.c:per_cpu_trap_init().
>
> There you can also ensure the value of vmalloc_end is <= FIXADDR_START.
>
> Finally probing can be used to fix yet another sin. For 64-bit kernels
> arch/mips/include/asm/processor.h defines TASK_SIZE:
>
> #define TASK_SIZE 0x10000000000UL
>
> This should turn into something like.
>
> #define TASK_SIZE (1UL << vmbits)
>
> This is also why I sugget to keep vmbits as 31, not 32. Hello S390 :-)
>
>> +static inline void cpu_set_vmbits(struct cpuinfo_mips *c)
>> +{
>> + if (cpu_has_64bits) {
>> + write_c0_entryhi(0x3ffffffffffff000ULL);
>> + back_to_back_c0_hazard();
>> + c->vmbits = fls64(read_c0_entryhi() & 0x3ffffffffffff000ULL);
>> + } else
>> + c->vmbits = 32;
>> +}
>
> With my changes suggested above this would need changing to something like:
>
> static inline void cpu_set_vmbits(struct cpuinfo_mips *c)
> {
> if (__NEED_VMBITS) {
> write_c0_entryhi(0x3ffffffffffff000ULL);
> back_to_back_c0_hazard();
> c->vmbits = fls64(read_c0_entryhi() & 0x3ffffffffffff000ULL);
>
> return;
> }
>
> BUG();
> }
>
>> #define R4K_OPTS (MIPS_CPU_TLB | MIPS_CPU_4KEX | MIPS_CPU_4K_CACHE \
>> | MIPS_CPU_COUNTER)
>>
>> @@ -967,6 +977,8 @@ __cpuinit void cpu_probe(void)
>> c->srsets = ((read_c0_srsctl() >> 26) & 0x0f) + 1;
>> else
>> c->srsets = 1;
>> +
>> + cpu_set_vmbits(c);
>
> I think a name like cpu_probe_vmbits() would be clearer.
>
> Thanks,
>
> Ralf
>
>
