Re: [PATCH] EFI: Do not use __pa() to get the physical address of anioremapped memory range

[huang ying]

On Mon, Sep 12, 2011 at 10:52 PM, Matt Fleming <matt@xxxxxxxxxxxxxxxxx> wrote:
> On Fri, 2011-09-02 at 13:12 +0800, huang ying wrote:
>> On Thu, Sep 1, 2011 at 8:28 PM, Matt Fleming <matt@xxxxxxxxxxxxxxxxx> wrote:
>> >
>> > Hmm.. does anyone know why we ioremap_cache() the memory on
>> > CONFIG_X86_32 instead of ioremap_nocache()? In the case of
>> > EFI_MEMORY_MAPPED_IO the memory really needs to be uncached. Then if
>> > we've ioremap'd the memory we should skip set_memory_uc() altogether,
>> > no?
>>
>> Because whether the mapping should be cached is determined by md->attr
>> instead of md->type. ÂAnd besides UC, we may add WC, etc support.
>
> Confused.
>
> The CONFIG_X86_64 version of efi_ioremap() looks like this,
>
> void __iomem *__init efi_ioremap(unsigned long phys_addr, unsigned long size,
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â u32 type)
> {
> Â Â Â Âunsigned long last_map_pfn;
>
> Â Â Â Âif (type == EFI_MEMORY_MAPPED_IO)
> Â Â Â Â Â Â Â Âreturn ioremap(phys_addr, size);
>
> Which uses md->type to figure out if we should call ioremap(), which on
> x86 is #define'd to ioremap_nocache(). CONFIG_X86_32 doesn't do this,
> but it looks to me like it should.

I don't think this type based solution is the perfect one.

Best Regards,
Huang Ying
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/