From 43fb2387d0774a36f450b50d538cee84cf83858e Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Fri, 10 Aug 2007 22:31:08 +0200 Subject: [PATCH] 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 Signed-off-by: Linus Torvalds --- Documentation/i386/zero-page.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) 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 @@ +--------------------------------------------------------------------------- +!!!!!!!!!!!!!!!WARNING!!!!!!!! +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. +!!!!!!!!!!!!!WARNING!!!!!!!!!!! +---------------------------------------------------------------------------- + Summary of boot_params layout (kernel point of view) ( collected by Hans Lermen and Martin Mares )