Re: [uml-user] UML with kernel 2.6.38 does not work a machines running linux kernel 3.1.0

[richard -r. w. <ric...@gm...>]

So, you're using gcc 4.5. You have to apply the patch below to your UML kernel.
Anyway, consider using a recent UML kernel. Or at least one which an
active stable tree.

commit 534e3adbd22efa327e6ff27cf2d8ebaad8382ecd
Author: Richard Weinberger <ri...@no...>
Date:   Wed Apr 27 15:26:54 2011 -0700

    um: adjust current_thread_info() for newer gcc versions

    In some cases gcc >= 4.5.2 will optimize away current_thread_info().  To
    prevent gcc from doing so the stack address has to be obtained via inline
    asm.

    Signed-off-by: Richard Weinberger <ri...@no...>
    Acked-by: Kirill A. Shutemov <ki...@sh...>
    Signed-off-by: Andrew Morton <ak...@li...>
    Signed-off-by: Linus Torvalds <tor...@li...>

diff --git a/arch/um/include/asm/thread_info.h
b/arch/um/include/asm/thread_info.h
index e2cf786..5bd1bad 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -49,7 +49,10 @@ static inline struct thread_info *current_thread_info(void)
 {
        struct thread_info *ti;
        unsigned long mask = THREAD_SIZE - 1;
-       ti = (struct thread_info *) (((unsigned long) &ti) & ~mask);
+       void *p;
+
+       asm volatile ("" : "=r" (p) : "0" (&ti));
+       ti = (struct thread_info *) (((unsigned long)p) & ~mask);
        return ti;
 }

-- 
Thanks,
//richard