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authorH. Peter Anvin <hpa@zytor.com>2007-07-11 12:18:33 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-12 10:55:54 -0700
commit85414b693ac037d709582a167a330db3a5d186d8 (patch)
tree78836556d59e28c335d2ba5be347c06f4298432e
parent1d67953f2bda8876045c24ae58841f27d9bb7572 (diff)
Define zero-page offset 0x1e4 as a scratch field, and use it
The relocatable kernel code needs a scratch field for the decompressor to determine its own location. It was using a location inside struct screen_info; reserve a free location and document it as scratch instead. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Documentation/i386/zero-page.txt1
-rw-r--r--arch/i386/boot/compressed/head.S6
-rw-r--r--arch/x86_64/boot/compressed/head.S6
3 files changed, 7 insertions, 6 deletions
diff --git a/Documentation/i386/zero-page.txt b/Documentation/i386/zero-page.txt
index c04a421f4a7..75b3680c41e 100644
--- a/Documentation/i386/zero-page.txt
+++ b/Documentation/i386/zero-page.txt
@@ -37,6 +37,7 @@ Offset Type Description
0x1d0 unsigned long EFI memory descriptor map pointer
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)
0x1e9 unsigned char number of entries in EDDBUF (below)
0x1ea unsigned char number of entries in EDD_MBR_SIG_BUFFER (below)
diff --git a/arch/i386/boot/compressed/head.S b/arch/i386/boot/compressed/head.S
index 3517a32aaf4..f35ea223752 100644
--- a/arch/i386/boot/compressed/head.S
+++ b/arch/i386/boot/compressed/head.S
@@ -45,10 +45,10 @@ startup_32:
* at and where we were actually loaded at. This can only be done
* with a short local call on x86. Nothing else will tell us what
* address we are running at. The reserved chunk of the real-mode
- * data at 0x34-0x3f are used as the stack for this calculation.
- * Only 4 bytes are needed.
+ * data at 0x1e4 (defined as a scratch field) are used as the stack
+ * for this calculation. Only 4 bytes are needed.
*/
- leal 0x40(%esi), %esp
+ leal (0x1e4+4)(%esi), %esp
call 1f
1: popl %ebp
subl $1b, %ebp
diff --git a/arch/x86_64/boot/compressed/head.S b/arch/x86_64/boot/compressed/head.S
index f9d5692a010..1312bfaff30 100644
--- a/arch/x86_64/boot/compressed/head.S
+++ b/arch/x86_64/boot/compressed/head.S
@@ -46,10 +46,10 @@ startup_32:
* at and where we were actually loaded at. This can only be done
* with a short local call on x86. Nothing else will tell us what
* address we are running at. The reserved chunk of the real-mode
- * data at 0x34-0x3f are used as the stack for this calculation.
- * Only 4 bytes are needed.
+ * data at 0x1e4 (defined as a scratch field) are used as the stack
+ * for this calculation. Only 4 bytes are needed.
*/
- leal 0x40(%esi), %esp
+ leal (0x1e4+4)(%esi), %esp
call 1f
1: popl %ebp
subl $1b, %ebp