Adding members to struct cpu_functions

[Guillaume Ballet]

On Mon, Oct 12, 2009 at 11:29 PM, Mark Tinguely <tinguely at casselton.net> wrote:
>
>>  As a result, extending the struct cpu_functions is not a good thing
>>  either, for the same reason. The compiler can not inline a call
>>  through a function pointer.
>>
>>  In which case, why not create a bunch of headers files with the
>>  pattern cpufunc_myarch.h, in which all functions would be declared
>>  inline? Something like:
>>
>>  static inline l2_l_entry(vm_addr_t pa, int prot, int cache);
>>  static inline l2_s_entry(vm_addr_t pa, int prot, int cache);
>>  ...
>>  which would then be included by pmap.c and friends.
>
> I think they need to be regular function calls because assembly routines
> call the per-cpu functions. A few simple macros would save the branch to NOP
> functions.
>

I'm not sure what you mean by that: would macros be ok, in your
opinion? I am a bit puzzled because I see a contradiction with the
previous sentence that requires the functions to be callable from the
assembly code. Obviously I am misinterpreting, so would you mind
clarifying, please?

I think it is important to notice that even though cache management
relies a lot on assembly function, I haven't found any page table
management done in assembly past locore.S. I think using macros for
page table management functions can be done. For cache management,
however, I agree that having different pmap.c files is probably the
way to go. In both cases, I am still curious to see what Nathan will
come up with.

I took a more thorough look at pmap, and there is indeed lots of
machine-specific code, especially at the beginning. And when it comes
to cpufunc, it's all about #ifdefs. Since I'm still working on the
cleanup for the beagleboard, I will declare cpufuncs in an
armv6-specific file. Let's call it cpufunc_armv6.c. I am struggling
with another MMU problem at the moment, but I'll try to come up asap
with a patch for pmap.c. It will replace hardcoded values with
machine-defined macros, for reference.

Guillaume