On Wed, Nov 05, 2008 at 08:10:30PM -0800, David Miller wrote:
> From: Robert Reif <reif@xxxxxxxxxxxxx>
> Date: Wed, 05 Nov 2008 22:03:52 -0500
>
> > sparc has failed to boot recently and I bisected it down to this patch:
> ...
> > sparc: correct section of current_pc()
> ...
> > Reverting this patch gets current git booting again.
>
> Thanks for tracking this down. I'll take a look and if I
> can't figure it out I'll revert.
The commit looks like this:
--- a/arch/sparc/kernel/head.S
+++ b/arch/sparc/kernel/head.S
@@ -465,6 +465,7 @@ gokernel:
mov %o7, %g4 ! Save %o7
/* Jump to it, and pray... */
+ __INIT
current_pc:
call 1f
nop
So the original code assumed that after executing "mov %o7, %g4"
it would execute "call 1f".
But chaning section breaks this assumption and the boot fails.
The code at the label gokernel: all looks like it belongs to __HEAD
but I do not know about the traptable just above it.
If we ignore the traptable I think the below is the more correct approach:
diff --git a/arch/sparc/kernel/head.S b/arch/sparc/kernel/head.S
index 2fe2c11..ae479a5 100644
--- a/arch/sparc/kernel/head.S
+++ b/arch/sparc/kernel/head.S
@@ -72,7 +72,7 @@ sun4e_notsup:
.align 4
/* The Sparc trap table, bootloader gives us control at _start. */
- .text
+ __HEAD
.globl start, _stext, _start, __stext
.globl trapbase
_start: /* danger danger */
@@ -465,7 +465,6 @@ gokernel:
mov %o7, %g4 ! Save %o7
/* Jump to it, and pray... */
- __INIT
current_pc:
call 1f
nop
[Copy'n'paste so it will not apply - because I do not think it is enough]
But someone that knows this stuff should fix it.
I checked vmlinux.lds.S and I can see that sparc needs to have
.head.text added before we can use __HEAD in assembler.
I assume it is something like this:
diff --git a/arch/sparc/kernel/vmlinux.lds.S b/arch/sparc/kernel/vmlinux.lds.S
index b1002c6..12d1be0 100644
--- a/arch/sparc/kernel/vmlinux.lds.S
+++ b/arch/sparc/kernel/vmlinux.lds.S
@@ -10,8 +10,11 @@ jiffies = jiffies_64 + 4;
SECTIONS
{
. = 0x10000 + SIZEOF_HEADERS;
- .text 0xf0004000 :
- {
+ .text.head 0xf0004000 : {
+ _text = .; /* Text and read-only data */
+ *(.text.head)
+ } : text = 0
+ .text : {
_text = .;
TEXT_TEXT
SCHED_TEXT
With this change we are then less dependent on link orderr which is a good thing.
Sam
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