Re: [PATCH 1/2] mtd: fix wrong usage of ioremap_nocache() in uclinux.c map driver

[Greg Ungerer <gerg@snapgear.com>]

Hi David,

On 07/07/12 01:55, David Woodhouse wrote:
> On Thu, 2012-05-10 at 16:55 +1000, gerg@snapgear.com wrote:
>> But if we want to use the uclinux.c mapping driver on real MMU enabled
>> systems we should be using phys_to_virt() for the translation, since
>> that is really what we are doing. So change it to do that.
>
> That seems wrong. On a highmem page, phys_to_virt() isn't valid. So at
> the very least, any usage of phys_to_virt() needs a stonking great
> comment explaining why it's always safe because it can never be used ona
> a highmem page.

The only VM based arch this driver can be configured for currently
is m68k (actually it is even more specific, only CONFIG_COLDFIRE).
And that doesn't support HIGHMEM.

Can the kernels data region (and the area immediately after it) be in
high memory?

Regards
Greg


  
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Greg Ungerer  --  Principal Engineer        EMAIL:     gerg@snapgear.com
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