[PATCH 08/13] [ARM] Make VMALLOC_END into a global variable if not defined

[Eric Miao]

On Wed, Jul 14, 2010 at 12:24 PM, Kyungmin Park <kmpark at infradead.org> wrote:
> On Wed, Jul 14, 2010 at 1:11 PM, Eric Miao <eric.miao at canonical.com> wrote:
>> On Wed, Jul 14, 2010 at 10:57 AM, Kyungmin Park <kmpark at infradead.org> wrote:
>>> Good idea!
>>> Each board can use each own vmalloc_end. no need to bound chip global
>>> vmalloc_end.
>>>
>>> On Wed, Jul 14, 2010 at 12:33 AM, Eric Miao <eric.miao at canonical.com> wrote:
>>>> Signed-off-by: Eric Miao <eric.miao at canonical.com>
>>>> ---
>>>>  arch/arm/include/asm/mach/arch.h |    1 +
>>>>  arch/arm/include/asm/pgtable.h   |    5 +++++
>>>>  arch/arm/kernel/setup.c          |    6 ++++++
>>>>  3 files changed, 12 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
>>>> index 52bea4c..2191d40 100644
>>>> --- a/arch/arm/include/asm/mach/arch.h
>>>> +++ b/arch/arm/include/asm/mach/arch.h
>>>> @@ -27,6 +27,7 @@ struct machine_class {
>>>>                                                 * page tabe entry      */
>>>>        const char              *name;          /* machine class name   */
>>>>        unsigned long           boot_params;    /* tagged list          */
>>>> +       unsigned long           vmalloc_end;    /* VMALLOC_END          */
>>>>
>>>>        void                    (*map_io)(void);/* IO mapping function */
>>>>        void                    (*init_irq)(void);
>>>> diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
>>>> index ab68cf1..478249a 100644
>>>> --- a/arch/arm/include/asm/pgtable.h
>>>> +++ b/arch/arm/include/asm/pgtable.h
>>>> @@ -40,6 +40,11 @@
>>>>  #define VMALLOC_START          (((unsigned long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
>>>>  #endif
>>>>
>>>> +#ifndef VMALLOC_END
>>>> +extern unsigned long vmalloc_end;
>>>> +#define VMALLOC_END (vmalloc_end)
>>>> +#endif
>>>> +
>>>>  /*
>>>>  * Hardware-wise, we have a two level page table structure, where the first
>>>>  * level has 4096 entries, and the second level has 256 entries.  Each entry
>>>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
>>>> index 295de99..672a8ec 100644
>>>> --- a/arch/arm/kernel/setup.c
>>>> +++ b/arch/arm/kernel/setup.c
>>>> @@ -95,6 +95,9 @@ EXPORT_SYMBOL(isa_dma_threshold);
>>>>  unsigned long max_dma_address = 0xffffffffUL;
>>>>  EXPORT_SYMBOL(max_dma_address);
>>>>
>>>> +unsigned long vmalloc_end = 0xffffffffUL;
>>>> +EXPORT_SYMBOL(vmalloc_end);
>>>
>>> At current code, 0xfe800000UL is the largest number. If we set end
>>> vmalloc_end to 0xffffffffUL and use it. maybe system can't boot.
>>> arch/arm/mach-loki/include/mach/vmalloc.h:#define VMALLOC_END   0xfe800000UL
>>>
>>
>> So the platform has to setup vmalloc correct :-)
>>
>>>> +
>>>>  #ifdef MULTI_CPU
>>>>  struct processor processor;
>>>>  #endif
>>>> @@ -684,6 +687,9 @@ void __init setup_arch(char **cmdline_p)
>>>>        class = mdesc->class;
>>>>        machine_name = mdesc->name;
>>>>
>>>> +       if (class)
>>>> +               vmalloc_end = class->vmalloc_end;
>>>
>>> Don't check 'if (class->vmalloc_end)'?
>>>
>>
>> Better to check that, but not sure if that's necessary. I'd expect
>> every machine_class to get this correct, instead of leaving it
>> uninitialized (i.e. == 0).
>>
> Then this patch is intermediate patch and VMALLOC_END will be removed finally?
> At first I understand there's global VMALLOC_END on each chip and each
> board can override it.
>

Yes. Currently, each sub-arch defines their own VMALLOC_END in
arch/arm/mach-*/include/mach/vmalloc.h. To move all to use a variable
version of VMALLOC_END would be tedious work and also requires
every sub-arch to have their own 'struct machine_class' ready. So the
idea here is for each sub-arch to:

1) have their 'struct machine_class' ready
2) encode the correct VMALLOC_END value into that
3) remove the definition from vmalloc.h
4) and the variable version will be used

Each sub-arch can do this without affecting others.