Re: [PATCH 5/5] x86_64 EFI support -v3: EFI document

[Huang, Ying]

On Mon, 2007-07-30 at 22:40 -0600, Eric W. Biederman wrote:
> "Huang, Ying" <ying.huang@xxxxxxxxx> writes:
> 
> > This patch adds document for EFI x86_64 support. The boot parameters
> > added are documented in Documentation/i386/zero-page.txt. The setup
> > and operation guide of EFI based system is documented in
> > Documentation/x86_64/uefi.txt.
> >
> > Signed-off-by: Chandramouli Narayanan <mouli@xxxxxxxxxxxxxxx>
> > Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>
> >
> > ---
> >
> >  i386/zero-page.txt |   18 ++++++++++++++----
> >  x86_64/uefi.txt    |   42 ++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 56 insertions(+), 4 deletions(-)
> >
> > Index: linux-2.6.23-rc1/Documentation/i386/zero-page.txt
> > ===================================================================
> > --- linux-2.6.23-rc1.orig/Documentation/i386/zero-page.txt 2007-07-30
> > 11:28:45.000000000 +0800
> > +++ linux-2.6.23-rc1/Documentation/i386/zero-page.txt 2007-07-30
> > 11:29:28.000000000 +0800
> > @@ -31,11 +31,11 @@
> >   0xb0 - 0x13f		Free. Add more parameters here if you really need them.
> >   0x140- 0x1be		EDID_INFO Video mode setup
> >  
> > -0x1c4	unsigned long	EFI system table pointer
> > -0x1c8	unsigned long	EFI memory descriptor size
> > -0x1cc	unsigned long	EFI memory descriptor version
> > +0x1c4	unsigned long	EFI system table pointer*
> > +0x1c8	unsigned long	EFI memory descriptor size*
> > +0x1cc	unsigned long	EFI memory descriptor version*
> >  0x1d0	unsigned long	EFI memory descriptor map pointer
> > -0x1d4	unsigned long	EFI memory descriptor map size
> > +0x1d4	unsigned long	EFI memory descriptor map size*
> >  0x1e0	unsigned long	ALT_MEM_K, alternative mem check, in Kb
> >  0x1e4	unsigned long	Scratch field for the kernel setup code
> >  0x1e8	char		number of entries in E820MAP (below)
> > @@ -87,3 +87,13 @@
> >  0x2d0 - 0xd00		E820MAP
> >  0xd00 - 0xeff		EDDBUF (edd.S) for disk signature read sector
> >  0xd00 - 0xeeb		EDDBUF (edd.S) for edd data
> > +
> > +Changes for x86_64 implementation:
> > +---------------------------------
> > +For alignment purposes, the following parameters are rearranged.
> > +
> > +0x1b8	unsigned long	EFI system table pointer
> > +0x1c0	unsigned long	EFI Loader signature
> > +0x1c4	unsigned long	EFI memory descriptor size
> > +0x1c8	unsigned long	EFI memory descriptor version
> > +0x1cc	unsigned long	EFI memory descriptor map size
> 
> Huh?  It is the same protocol.  Unless there are specific issues such
> as pointers being to small we should remain 100% the same for both
> arch/i386 and arch/x86_64   This variation looks like a serious
> bug.

The parameters are rearranged, because the pointer is too small. For
example, the EFI system table pointer is 8 bytes in x86_64, while it is
4 bytes in i386.

Best Regards,
Huang Ying
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