On Wed, Oct 13, 2010 at 08:29:35PM -0500, Dale Rahn wrote:
On Thu, Oct 14, 2010 at 01:50:36AM +0200, Tobias Ulmer wrote:
I'm currently loading the kernel at a fixed start address using u-boot.
There's no relocation going on.
Accessing anything in the data segment leads to crashes due to file- and
address offsets desyncing.
The patch below fixes this issue and, as a bonus, syncs the code with
the comment.
Possibly affected are armish, beagle, gumstix, palm and zaurus
Index: arch/arm/conf/ldscript.tail
===
RCS file:
/srv/boron/data/vcs/cvs/openbsd/src/sys/arch/arm/conf/ldscript.tail,v
retrieving revision 1.4
diff -u -p -r1.4 ldscript.tail
--- arch/arm/conf/ldscript.tail 27 Jun 2009 14:44:39 - 1.4
+++ arch/arm/conf/ldscript.tail 13 Oct 2010 23:17:30 -
@@ -5,7 +5,7 @@
PROVIDE (etext = .);
/* Adjust the address for the data segment to start on the next page
boundary. */
- . = ALIGN(0x8000);
+ . = ALIGN(0x1000);
.data:
AT (LOADADDR(.text) + (ADDR(.data) - ADDR(.text)))
{
How are you loading the kernel with u-boot?
When I was doing this in the past, I was doing the following
$ ${OBJCOPY} -O binary bsd bsd.img
$ mkuboot -a arm -o linux -e ${KERNEL_BASE_PHYS} -l ${KERNEL_BASE_PHYS}
bsd.img bsd.umg
This method had no problem with the current 'alignment'
I create bsd.umg without the intermediate OBJCOPY step. I remember that
not going well when I first tried it, not sure why.
The load address is KERNEL_BASE_PHYS minus the ELF header. This works
just fine, except for that small data segment detail.
bsd.umg: bsd
${MKUBOOT} -a arm -o OpenBSD -e ${KERNEL_BASE_PHYS} -l `printf
0x%x $$((${KERNEL_BASE_PHYS}-${KERNEL_BASE_EOFF}))` bsd bsd.umg
I thought I recalled that the ldscript aligned the pages on 64k boundaries,
but that does not appear to be the case. Not certian why 32k would be
desireable.
Will look into this more.
Dale Rahn dr...@dalerahn.com
Here's some objdump -h output, first one without the patch:
Idx Name Size VMA LMA File off Algn
0 .start00a8 00801000 00801000 1000 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .text 001f1c77 c08010a8 008010a8 10a8 2**5
CONTENTS, ALLOC, LOAD, READONLY, CODE
2 .data 8f70 c09f8000 009f8000 001f3000 2**2
CONTENTS, ALLOC, LOAD, DATA
Idx Name Size VMA LMA File off Algn
0 .start00a8 00801000 00801000 1000 2**0
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .text 001f20eb c08010a8 008010a8 10a8 2**5
CONTENTS, ALLOC, LOAD, READONLY, CODE
2 .data 8f70 c09f4000 009f4000 001f4000 2**2
CONTENTS, ALLOC, LOAD, DATA
(sdram starts at 0x0, u-boot occupies 0-8M - I like to keep its illegal
instruction handler etc for the time being)
