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>
diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
index 35985b3..2f75e75 100644
--- a/Documentation/i386/boot.txt
+++ b/Documentation/i386/boot.txt
@@ -168,6 +168,8 @@
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 @@
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 @@
- 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 @@
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