Al Viro wrote:
> On Thu, Oct 25, 2007 at 09:01:52PM +0530, Balbir Singh wrote:
>
>> Thats nice, I wonder why I missed them searching on lkml in my gmail box
>> :(
>>
>> Is __arch_um__ the right thing to do or BITS_PER_LONG == 32? I prefer
>> BITS_PER_LONG == 32 over #if defined(__i386__) || defined(__arch__um__).
>> I guess its a matter of personal preference.
>
> Huh?
>
> a) we really shouldn't mess with compiler defines (i.e. we should not
> undef __i386__ or __x86_64__)
>
I agree
> b) I'd rather have __arch_um__ mentioned explicitly in 3 places where
> we do care about difference between i386 and uml/i386 than have certain
> to be forgotten rules for places like include/asm-x86
>
> c) if you look at those places, you'll see
> * drivers/char/mem.c::uncached_access(). Really per-architecture
> and I wonder if it might be include/asm-* fodder...
> * kernel/signal.c debugging printks. Should die or be sanitized, IMO.
> * raid6 algorithms. Hell knows - immediate reason why we don't do
> those on uml is the lack of kernel_fpu_begin()/kernel_fpu_end() (and
> boot_cpu_has(), but that's easier to add). Do we care to implement that
> stuff?
>
I suspect that list might grow and anybody writing i386 or x86_64 code
will need to double check if the code will work under __arch_um__.
Probably worth documenting somewhere.
> That's _all_. Nothing else has to care.
>
:-)
--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
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