Re: [Xenomai-core] pgprot_noncached for io-remapping?

[Jan Kiszka <jan.kiszka@domain.hid>]

[-- Attachment #1: Type: text/plain, Size: 807 bytes --]

Philippe Gerum wrote:
> Jan Kiszka wrote:
>> Hi,
>>
>> doesn't this patch [1] have some relevance for us as well? As we use
>> xnarch_remap_io_page_range also for non-IO memory, I'm hesitating to
>> suggest that we apply this unconditionally at xnarch level. Ideas welcome.
>>
> 
> Yes, I think it makes a lot of sense on powerpc at least, since doing so will
> set the PAGE_GUARDED bit as well, and we obviously want to avoid any
> out-of-order access of I/O memory.
> 
> (I don't see the reason to force the VM_RESERVED and VM_IO on the vma though,
> since remap_pfn_range will do it anyway.)

No, I was talking about cases where we may pass kmalloc'ed memory to
xnarch_remap_io_page_range. In that case, caching and out-of-order
access may be desired for performance reasons.

Jan


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 254 bytes --]