On Mon, 27 Oct 2014, Juergen Gross wrote:
> At the moment there are a lot of places that handle setting or getting
> the page cache mode by treating the pgprot bits equal to the cache mode.
> This is only true because there are a lot of assumptions about the setup
> of the PAT MSR. Otherwise the cache type needs to get translated into
> pgprot bits and vice versa.
>
> This patch tries to prepare for that by introducing a separate type
> for the cache mode and adding functions to translate between those and
> pgprot values.
>
> To avoid too much performance penalty the translation between cache mode
> and pgprot values is done via tables which contain the relevant
> information. Write-back cache mode is hard-wired to be 0, all other
> modes are configurable via those tables. For large pages there are
> translation functions as the PAT bit is located at different positions
> in the ptes of 4k and large pages.
I'm fine with the approach itself. Though I wish you had split this
patch in several sanely to review pieces.
- Introduce enums, helper functions etc. which basically reflect
the state of today
- Change the usage sites to use the enums and helpers
- Convert the enum/helper implementation to the new scheme
- Split out the printk change
...
Thanks,
tglx
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