Hi Peter,
Le 29/02/2012 17:42, Peter Barada a écrit :
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>"?
I routinely use ELDK42 (4.2.2 toochain) and stcok (linaro) Ubuntu
(4.6.1). I don't remember having hit this issue -- although I am hitting
another one where breakpoints are set 4 or 8 bytes further than they
should, but the symbols themselves are ok; but I rarely use global .data
or .bss symbols, so I may have missed the issue.
Anyway, 'help add-symbol-file' says a single address applies to
consecutive sections, so until it is sorted out with the GDB people why
this does not work, my NAK still holds.
Amicalement,
--
Albert.
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