update boot spec to 2.07

Updates for version 2.07 of the boot protocol.  This includes:

load_flags.KEEP_SEGMENTS- flag to request/inhibit segment reloads
hardware_subarch	- what subarchitecture we're booting under
hardware_subarch_data	- per-architecture data

The intention of these changes is to make booting a paravirtualized
kernel work via the normal Linux boot protocol.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 33 insertions, 1 deletions

diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
index 35985b34d5a6..2f75e750e4f5 100644
--- a/Documentation/i386/boot.txt
+++ b/Documentation/i386/boot.txt
@@ -168,6 +168,8 @@ Offset	Proto	Name		Meaning
 0234/1  2.05+   relocatable_kernel Whether kernel is relocatable or not
 0235/3  N/A     pad2            Unused
 0238/4  2.06+   cmdline_size    Maximum size of the kernel command line
+023C/4  2.07+   hardware_subarch Hardware subarchitecture
+0240/8  2.07+   hardware_subarch_data Subarchitecture-specific data
 
 (1) For backwards compatibility, if the setup_sects field contains 0, the
     real value is 4.
@@ -204,7 +206,7 @@ boot loaders can ignore those fields.
 
 The byte order of all fields is littleendian (this is x86, after all.)
 
-Field name:     setup_secs
+Field name:     setup_sects
 Type:           read
 Offset/size:    0x1f1/1
 Protocol:       ALL
@@ -356,6 +358,13 @@ Protocol:	2.00+
         - If 0, the protected-mode code is loaded at 0x10000.
         - If 1, the protected-mode code is loaded at 0x100000.
 
+  Bit 6 (write): KEEP_SEGMENTS
+        Protocol: 2.07+
+        - if 0, reload the segment registers in the 32bit entry point.
+        - if 1, do not reload the segment registers in the 32bit entry point.
+                Assume that %cs %ds %ss %es are all set to flat segments with
+                a base of 0 (or the equivalent for their environment).
+
   Bit 7 (write): CAN_USE_HEAP
         Set this bit to 1 to indicate that the value entered in the
         heap_end_ptr is valid.  If this field is clear, some setup code
@@ -480,6 +489,29 @@ Protocol:	2.06+
   cmdline_size characters. With protocol version 2.05 and earlier, the
   maximum size was 255.
 
+Field name:     hardware_subarch
+Type:           write
+Offset/size:    0x23c/4
+Protocol:       2.07+
+
+  In a paravirtualized environment the hardware low level architectural
+  pieces such as interrupt handling, page table handling, and
+  accessing process control registers needs to be done differently.
+
+  This field allows the bootloader to inform the kernel we are in one
+  one of those environments.
+
+  0x00000000    The default x86/PC environment
+  0x00000001    lguest
+  0x00000002    Xen
+
+Field name:     hardware_subarch_data
+Type:           write
+Offset/size:    0x240/8
+Protocol:       2.07+
+
+  A pointer to data that is specific to hardware subarch
+
 
 **** THE KERNEL COMMAND LINE