path: root/Documentation
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authorAndi Kleen <ak@suse.de>2007-08-10 22:31:08 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-08-11 15:58:14 -0700
commit43fb2387d0774a36f450b50d538cee84cf83858e (patch)
tree2a7c894bb93aac523cc2228b5249e659a7df3a9b /Documentation
parentd3f7eae182b04997be19343a23f7009170f4f7a5 (diff)
i386: Add warning in Documentation that zero-page is not a stable ABI
Some people writing boot loaders seem to falsely belief the 32bit zero page is a stable interface for out of tree code like the real mode boot protocol. Add a comment clarifying that is not true. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/i386/zero-page.txt b/Documentation/i386/zero-page.txt
index 75b3680c41e..6c0817c4568 100644
--- a/Documentation/i386/zero-page.txt
+++ b/Documentation/i386/zero-page.txt
@@ -1,3 +1,13 @@
+The zero page is a kernel internal data structure, not a stable ABI. It might change
+without warning and the kernel has no way to detect old version of it.
+If you're writing some external code like a boot loader you should only use
+the stable versioned real mode boot protocol described in boot.txt. Otherwise the kernel
+might break you at any time.
Summary of boot_params layout (kernel point of view)
( collected by Hans Lermen and Martin Mares )