Hello list,
inside the automatic U-Boot patch tracking system a new ticket [DNX#2006040142000151] was created:
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First Question:
If I have understood everything correctly, u-boot ALWAYS relocates itselfs to RAM.
This is the code in Start.S in cpu/arm920t that makes the relocation.
relocate: /* relocate U-Boot to RAM */ adr r0, _start /* r0 <- current position of code */ ldr r1, _TEXT_BASE /* test if we run from flash or RAM */ cmp r0, r1 /* don't reloc during debugaitor
This is how I get the values that _start and _TEXT_BASE take:
arm-unknown-linux-gnu-gdb u-boot GNU gdb 6.2.1 Copyright 2004 Free Software Foundation, Inc. ... This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-unknown-linux-gnu"... (gdb) info address _start Symbol "_start" is at 0x8f00000 in a file compiled without debugging. (gdb) info address _TEXT_BASE Symbol "_TEXT_BASE" is at 0x8f00040 in a file compiled without debugging. (gdb) x/1xw 0x8f00040 0x8f00040 <_TEXT_BASE>: 0x08f00000 (gdb)
Both addresses TEXT_BASE & _start are SDRAM. According to this, this code will never relocate. Is this correct ?.
u-boot$ arm-unknown-linux-gnu-objdump -h u-boot u-boot: file format elf32-littlearm Sections: Idx Name Size VMA LMA File off Algn 0 .text 000138a4 08f00000 08f00000 00008000 2**5
What I conclude is that the binary is prepared to be loaded and executed only from SDRAM. In fact, IŽve loaded u-boot in sdram (0x8f00000) using bdi2000, I have defined CONFIG_SKIP_LOWLEVEL_INIT and CONFIG_SKIP_RELOCATE_UBOOT and I have been able to debug u-boot using gdb. I know this is not the right way to debug u-boot.
In conclusion, there are two things I don't understand:
- I think that LMA address of text section should be Flash 0x10000000.
Because the code must be loaded in non-volatile memory. VMA of course, should be SDRAM 0x8f00000.
- I think that the code that
makes the relocation must be loaded and executed from flash. VMA 0x10000000 and LMA 0x10000000.
Second Question.
You have told me that:
But for that you have to tell the debugger that the code is running > from an address that is different from the link address).
This is what IŽve done:
iim@viggen:~/.../u-boot-1.1.3$ arm-unknown-linux-gnu-gdb u-boot GNU gdb 6.3 ... This GDB was configured as "--host=i686-pc-linux-gnu --target=arm-unknown-linux-gnu"... (gdb) symbol-file Discard symbol table from `/.../u-boot-1.1.3/u-boot'? (y or n) y No symbol file now. (gdb) add-symbol-file u-boot 0x0000 add symbol table from file "u-boot" at .text_addr = 0x0 (y or n) y Reading symbols from /.../u-boot-1.1.3/u-boot...done. (gdb) b _start_armboot
Breakpoint 1 at 0x8f00394: file /.../u-boot-1.1.3/cpu/arm920t/start.S, line 435. (gdb) target remote 192.168.1.5:2001 Remote debugging using 192.168.1.5:2001 0x08f001c0 in ?? () (gdb) c Continuing.
But the breakpoint is still in sdram (0x8f00394), and the program doesnŽt stop in the breakpoint.
Regards.
Ioritz.
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Your U-Boot support team