[U-Boot] [PATCH] ARM: Add .data/.rodata/.bss section starts to gd_t

[Peter Barada]

On 02/28/2012 05:04 PM, Albert ARIBAUD wrote:
> Hi Peter,
>
> Le 27/02/2012 23:00, Peter Barada a écrit :
>> When debugging u-boot, after relocation its tedious to calculate positions
>> of the various sections (.data, .rodata, .bss).  To make it easier, add
>> the structure "sections" to gd_t that contains the relocated start of
>> those sections.  Then the gdb command "add-symbol-file" can by used with
>> "-s<section>  <address>" that corresponds to the values in gd_t->sections.
> NAK until I get an explanation and usage scenario for this, because I've 
> never had to do calculations on sections so far, so I want to understand 
> why it would be needed.
>
> Amicalement,
Weird.  Digging further its looking more like a problem with GDB...

I'm using the CodeSourcery 2009q1-203 toolchain (for ARM), and
"add-symbol-file u-boot 0x...." only relocated symbols in the .text
segment, not .data, .rodata, and .bss sections.  Looking at newer
toolchains (CodeSourcery 2011.09-70) I see even stranger results:

Current directory is /home/peter/work/logic/git/u-boot-branches/
GNU gdb (Sourcery CodeBench Lite 2011.09-70) 7.2.50.20100908-cvs
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "--host=i686-pc-linux-gnu
--target=arm-none-linux-gnueabi".
For bug reporting instructions, please see:
<https://support.codesourcery.com/GNUToolchain/>...
Reading symbols from
/home/peter/work/logic/git/u-boot-branches/u-boot...done.
(gdb) info file
Symbols from "/home/peter/work/logic/git/u-boot-branches/u-boot".
Local exec file:
    `/home/peter/work/logic/git/u-boot-branches/u-boot', file type
elf32-littlearm.
    Entry point: 0x80100000
    0x80100000 - 0x80124a30 is .text
    0x80124a30 - 0x8012d43a is .rodata
    0x8012d43c - 0x8012d488 is .hash
    0x8012d488 - 0x8012dee0 is .data
    0x8012dee0 - 0x8012deec is .got.plt
    0x8012deec - 0x8012e544 is .u_boot_cmd
    0x8013354c - 0x8013362c is .dynsym
    0x8012e544 - 0x8013354c is .rel.dyn
    0x8012e544 - 0x80165388 is .bss
(gdb)(gdb) symbol-file
Discard symbol table from
`/home/peter/work/logic/git/u-boot-branches/u-boot'? (y or n) y
No symbol file now.
(gdb) *add-symbol-file u-boot 0x8ff8a000 -readnow -s .rodata 0x8FFAEA30
-s .data 0x8FFB7488 -s .bss 0x8FFB8544*
add symbol table from file "u-boot" at
    .text_addr = 0x8ff8a000
    .rodata_addr = 0x8ffaea30
    .data_addr = 0x8ffb7488
    .bss_addr = 0x8ffb8544
(y or n) y
Reading symbols from
/home/peter/work/logic/git/u-boot-branches/u-boot...expanding to full
symbols...done.
(gdb) *p &stdio_devices*
$26 = (struct stdio_dev *(*)[3]) *0x80131c0c*
(gdb) info sym stdio_devices
__rel_dyn_start + 14024 in section .rel.dyn
(gdb) info sym boards
boards in section .data
(gdb) p *&boards*
$27 = (struct board_id (*)[2][2]) *0x8ffb7ec0*
(gdb) shell nm u-boot | grep stdio_devices
*80131c0c* B stdio_devices
(gdb) shell nm u-boot | grep boards
*8012dec0* d boards
(gdb)

Note that "boards" gets properly relocated whereas "stdio_devices" does
not - apparently a lot (all?) of the .bss symbols are not properly
relocated.  Hmm, I wonder if this is caused by .rel.dyn overlaing .bss...

Which version of GDB are you using on ARM that properly relocates all
the sections after "add-symbol-file u-boot <addr>"?

-- 
Peter Barada
peter.barada at logicpd.com