Re: [PATCH -v2] EFI: Runtime services virtual mapping

From: Borislav Petkov
Date: Wed Sep 25 2013 - 01:46:55 EST

On Tue, Sep 24, 2013 at 05:12:26PM -0700, H. Peter Anvin wrote:
> I am starting to think that we really should explicitly pass along the
> EFI mappings to the secondary kernel. This will also help if we have to
> change the algorithm in a future kernel.

That would be the most flexible solution, sure.

> The most logical way to do this is to define a new setup_data type and
> pass the entire set of physical-to-virtual mappings that way.
> For example:
> struct efi_mapping {
> u64 va; /* Virtual start address */
> u64 pa; /* Physical start address */
> u64 len; /* Length in bytes */
> u64 type; /* Mapping type */
> u64 reserved[3]; /* Reserved, must be zero */
> };
> Adding some reserved fields seems like a prudent precaution;

... and making checking they're zeroed out initially so that I can use
them in the future, if needed :)

> the map shouldn't be all that large anyway.

Yeah, let me look at it in more detail when I get back - it shouldn't be
that hard to do.

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