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, 9 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index dcb0593b4a66..71c194db2e0a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2062,6 +2062,15 @@ config OLPC
           Add support for detecting the unique features of the OLPC
           XO hardware.
 
+config OLPC_OPENFIRMWARE
+        bool "Support for OLPC's Open Firmware"
+        depends on !X86_64 && !X86_PAE
+        default y if OLPC
+        help
+          This option adds support for the implementation of Open Firmware
+          that is used on the OLPC XO-1 Children's Machine.
+          If unsure, say N here.
+
 endif # X86_32
 
 config K8_NB