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Re: [Xen-devel] [PATCH 04/15] xen: mm: add ioremap_cache

On 7/12/2017 6:17 PM, Jan Beulich wrote:
Julien Grall <julien.grall@xxxxxxx> 07/11/17 10:15 PM >>>
On 07/09/2017 09:10 AM, Kai Huang wrote:
Currently Xen only has non-cacheable version of ioremap. Although EPC is
reported as reserved memory in e820 but it can be mapped as cacheable. This
patch adds ioremap_cache (cacheable version of ioremap).

Signed-off-by: Kai Huang <kai.huang@xxxxxxxxxxxxxxx>
   xen/arch/x86/mm.c      | 15 +++++++++++++--
   xen/include/xen/vmap.h |  1 +

First of all, this is common code and the "REST" maintainers should have
been CCed for this include.

But xen/include/xen/vmap.h is common code and going to break ARM. We
already have an inline implementation of ioremap_nocache. You should
move the definition in x86 specific headers.

Indeed, plus the ARM implementation actually shows how this would better
be done: Have a function allowing more than just true/false to be passed in,
to eventually also allow having ioremap_wc() and alike as wrappers. As long
as it's x86-specific I'd then also suggest calling the new wrapper function
ioremap_wb() (as "cache" may also mean WT).

Hi Jan,

Thanks for comments. I'll do as you suggested.



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