x86, olpc: Add support for calling into OpenFirmware

Add support for saving OFW's cif, and later calling into it to run OFW
commands.  OFW remains resident in memory, living within virtual range
0xff800000 - 0xffc00000.  A single page directory entry points to the
pgdir that OFW actually uses, so rather than saving the entire page
table, we grab and install that one entry permanently in the kernel's
page table.

This is currently only used by the OLPC XO.  Note that this particular
calling convention breaks PAE and PAT, and so cannot be used on newer
x86 hardware.

Signed-off-by: Andres Salomon <dilinger@queued.net>
LKML-Reference: <20100618174653.7755a39a@dev.queued.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt
index feb37e177010..cf5437deda81 100644
--- a/Documentation/x86/zero-page.txt
+++ b/Documentation/x86/zero-page.txt
@@ -18,6 +18,7 @@ Offset	Proto	Name		Meaning
 080/010 ALL     hd0_info        hd0 disk parameter, OBSOLETE!!
 090/010 ALL     hd1_info        hd1 disk parameter, OBSOLETE!!
 0A0/010 ALL     sys_desc_table  System description table (struct sys_desc_table)
+0B0/010 ALL     olpc_ofw_header OLPC's OpenFirmware CIF and friends
 140/080 ALL     edid_info       Video mode setup (struct edid_info)
 1C0/020 ALL     efi_info        EFI 32 information (struct efi_info)
 1E0/004 ALL     alk_mem_k       Alternative mem check, in KB