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authorJimi Xenidis <jimix@watson.ibm.com>2006-06-26 04:56:58 -0400
committerPaul Mackerras <paulus@samba.org>2006-06-28 15:18:53 +1000
commitd0b79c54fc14f1f2db64180a21b84146028c598b (patch)
tree26b3b74d80e96a7d7402723fbed90664147c016a
parentc0ce7d0886cf0c2579c604eac41a7e125bc0e96d (diff)
[POWERPC] Skip the "copy down" of the kernel if it is already at zero.
This patch allows the kernel to recognized that it was loaded at zero and the copy down of the image is unnecessary. This is useful for Simulators and kexec models. On a typical 3.8 MiB vmlinux.strip this saves about 2.3 million instructions. Signed-off-by: Paul Mackerras <paulus@samba.org>
-rw-r--r--arch/powerpc/kernel/head_64.S3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index da092429349..f2fab687a01 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -1664,6 +1664,9 @@ _STATIC(__after_prom_start)
/* i.e. where we are running */
/* the source addr */
+ cmpdi r4,0 /* In some cases the loader may */
+ beq .start_here_multiplatform /* have already put us at zero */
+ /* so we can skip the copy. */
LOAD_REG_IMMEDIATE(r5,copy_to_here) /* # bytes of memory to copy */
sub r5,r5,r27