mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-27 15:12:21 +00:00
a9aa392629
When this define was introduced, the idea was to provide a soft migration path for ARM boards to get adapted to the new relocation support. However, other recent changes led to a different implementation (ELF relocation), where this no longer works. By now CONFIG_SYS_ARM_WITHOUT_RELOC does not only not help any more, but it actually hurts because it obfuscates the actual code by sprinkling it with lots of dead and non-working debris. So let's make a clean cut and drop CONFIG_SYS_ARM_WITHOUT_RELOC. Signed-off-by: Wolfgang Denk <wd@denx.de> Tested-by: Heiko Schocher <hs@denx.de> Tested-by: Reinhard Meyer <u-boot@emk-elektronik.de>
194 lines
5.9 KiB
Text
194 lines
5.9 KiB
Text
To make relocation on arm working, the following changes are done:
|
|
|
|
At arch level: add linker flag -pie
|
|
|
|
This causes the linker to generate fixup tables .rel.dyn and .dynsym,
|
|
which must be applied to the relocated image before transferring
|
|
control to it.
|
|
|
|
These fixups are described in the ARM ELF documentation as type 23
|
|
(program-base-relative) and 2 (symbol-relative)
|
|
|
|
At cpu level: modify linker file and add a relocation and fixup loop
|
|
|
|
the linker file must be modified to include the .rel.dyn and .dynsym
|
|
tables in the binary image, and to provide symbols for the relocation
|
|
code to access these tables
|
|
|
|
The relocation and fixup loop must be executed after executing
|
|
board_init_f at initial location and before executing board_init_r
|
|
at final location.
|
|
|
|
At board level:
|
|
|
|
dram_init(): bd pointer is now at this point not accessible, so only
|
|
detect the real dramsize, and store it in gd->ram_size. Bst detected
|
|
with get_ram_size().
|
|
|
|
TODO: move also dram initialization there on boards where it is possible.
|
|
|
|
Setup of the the bd_t dram bank info is done in the new function
|
|
dram_init_banksize() called after bd is accessible.
|
|
|
|
At lib level:
|
|
|
|
Board.c code is adapted from ppc code
|
|
|
|
* WARNING ** WARNING ** WARNING ** WARNING ** WARNING ** WARNING ** WARNING *
|
|
|
|
Boards which are not fixed to support relocation will be REMOVED!
|
|
|
|
-----------------------------------------------------------------------------
|
|
|
|
For boards which boot from nand_spl, it is possible to save one copy
|
|
if CONFIG_SYS_TEXT_BASE == relocation address! This prevents that uboot code
|
|
is copied again in relocate_code().
|
|
|
|
example for the tx25 board:
|
|
|
|
a) cpu starts
|
|
b) it copies the first page in nand to internal ram
|
|
(nand_spl_code)
|
|
c) end executes this code
|
|
d) this initialize CPU, RAM, ... and copy itself to RAM
|
|
(this bin must fit in one page, so board_init_f()
|
|
don;t fit in it ... )
|
|
e) there it copy u-boot to CONFIG_SYS_NAND_U_BOOT_DST and
|
|
starts this image @ CONFIG_SYS_NAND_U_BOOT_START
|
|
f) u-boot code steps through board_init_f() and calculates
|
|
the relocation address and copy itself to it
|
|
|
|
If CONFIG_SYS_TEXT_BASE == relocation address, the copying of u-boot
|
|
in f) could be saved.
|
|
|
|
-----------------------------------------------------------------------------
|
|
|
|
TODO
|
|
|
|
- fill in bd_t infos (check)
|
|
- adapt all boards
|
|
|
|
- maybe adapt CONFIG_SYS_TEXT_BASE (this must be checked from board maintainers)
|
|
This *must* be done for boards, which boot from NOR flash
|
|
|
|
on other boards if CONFIG_SYS_TEXT_BASE = relocation baseaddr, this saves
|
|
one copying from u-boot code.
|
|
|
|
- new function dram_init_banksize() is actual board specific. Maybe
|
|
we make a weak default function in arch/arm/lib/board.c ?
|
|
|
|
-----------------------------------------------------------------------------
|
|
|
|
Relocation with NAND_SPL (example for the tx25):
|
|
|
|
- cpu copies the first page from NAND to 0xbb000000 (IMX_NFC_BASE)
|
|
and start with code execution on this address.
|
|
|
|
- The First page contains u-boot code from u-boot:nand_spl/nand_boot_fsl_nfc.c
|
|
which inits the dram, cpu registers, reloacte itself to CONFIG_SYS_TEXT_BASE and loads
|
|
the "real" u-boot to CONFIG_SYS_NAND_U_BOOT_DST and starts execution
|
|
@CONFIG_SYS_NAND_U_BOOT_START
|
|
|
|
- This u-boot does no RAM init, nor CPU register setup. Just look
|
|
where it has to copy and relocate itself to this address. If
|
|
relocate address = CONFIG_SYS_TEXT_BASE (not the same, as the
|
|
CONFIG_SYS_TEXT_BASE from the nand_spl code), then there is no need
|
|
to copy, just go on with bss clear and jump to board_init_r.
|
|
|
|
-----------------------------------------------------------------------------
|
|
|
|
How ELF relocations 23 and 2 work.
|
|
|
|
TBC
|
|
|
|
-------------------------------------------------------------------------------------
|
|
|
|
Debugging u-boot in RAM:
|
|
(example on the qong board)
|
|
|
|
a) add in config.mk:
|
|
|
|
PLATFORM_CPPFLAGS += -DDEBUG
|
|
|
|
-----------------
|
|
|
|
b) start debugger
|
|
|
|
arm-linux-gdb u-boot
|
|
|
|
[hs@pollux u-boot]$ arm-linux-gdb u-boot
|
|
GNU gdb Red Hat Linux (6.7-2rh)
|
|
Copyright (C) 2007 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-linux".
|
|
The target architecture is set automatically (currently arm)
|
|
..
|
|
(gdb)
|
|
|
|
-----------------
|
|
|
|
c) connect to target
|
|
|
|
target remote bdi10:2001
|
|
|
|
(gdb) target remote bdi10:2001
|
|
Remote debugging using bdi10:2001
|
|
0x8ff17f10 in ?? ()
|
|
(gdb)
|
|
|
|
-----------------
|
|
|
|
d) discard symbol-file
|
|
|
|
(gdb) symbol-file
|
|
Discard symbol table from `/home/hs/celf/u-boot/u-boot'? (y or n) y
|
|
No symbol file now.
|
|
(gdb)
|
|
|
|
-----------------
|
|
|
|
e) load new symbol table:
|
|
|
|
(gdb) add-symbol-file u-boot 0x8ff08000
|
|
add symbol table from file "u-boot" at
|
|
.text_addr = 0x8ff08000
|
|
(y or n) y
|
|
Reading symbols from /home/hs/celf/u-boot/u-boot...done.
|
|
(gdb) c
|
|
Continuing.
|
|
^C
|
|
Program received signal SIGSTOP, Stopped (signal).
|
|
0x8ff17f18 in serial_getc () at serial_mxc.c:192
|
|
192 while (__REG(UART_PHYS + UTS) & UTS_RXEMPTY);
|
|
(gdb)
|
|
|
|
add-symbol-file u-boot 0x8ff08000
|
|
^^^^^^^^^^
|
|
get this address from u-boot debug printfs
|
|
|
|
U-Boot 2010.06-rc2-00009-gf77b8b8-dirty (Jun 22 2010 - 09:43:46)
|
|
|
|
U-Boot code: A0000000 -> A0058BAC BSS: -> A0061F10
|
|
CPU: Freescale i.MX31 at 398 MHz
|
|
Board: DAVE/DENX Qong
|
|
mon: FFFFFFFF gd->monLen: 00061F10
|
|
Top of RAM usable for U-Boot at: 90000000
|
|
LCD panel info: 640 x 480, 16 bit/pix
|
|
Reserving 600k for LCD Framebuffer at: 8ff6a000
|
|
Reserving 391k for U-Boot at: 8ff08000
|
|
^^^^^^^^
|
|
Reserving 1280k for malloc() at: 8fdc8000
|
|
Reserving 24 Bytes for Board Info at: 8fdc7fe8
|
|
Reserving 52 Bytes for Global Data at: 8fdc7fb4
|
|
New Stack Pointer is: 8fdc7fb0
|
|
RAM Configuration:
|
|
Bank #0: 80000000 256 MiB
|
|
relocation Offset is: eff08000
|
|
mon: 00058BAC gd->monLen: 00061F10
|
|
Now running in RAM - U-Boot at: 8ff08000
|
|
^^^^^^^^
|
|
|
|
Now you can use gdb as usual :-)
|