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

[Borislav Petkov]

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.

Thanks.
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