I had some time this weekend (while beeing grilled by the sun on my
balcony) to work on another thing that did not work correct and that I
did not understand (Now I do, I least I hope ;-)
As said before in this thread, I wanted to distribute Code in two
different memory areas because this needs to be done so that pic32
startup code works correctly.
But when I linked my binary the elf-file had always a startup address
somewhere in the wrong memory area.
This is what I tried:
procedure reset; assembler; nostackframe; public name'_reset';
asm
.section ".reset,\"ax\",@progbits"
la $k0, _startup
jr $k0 //Jump to startup code
nop
.text
end;
but this does not what I expected. I thought that the code would go to
the segment I assigned to .reset in the linker script (that worked) and
I also thought that the symbol _reset would point to this location
... which did not happen ...
the symbol _reset will get defined somewhere in the .text segment even
though the code resides in another segment (please see the generated
assembler listing created by inline asm later in this mail). All in all
that makes perfect sense, the compiler is doing exactly what I wrote but
not what I wanted ;-) ;-)
So I created a 'real' assembler file for the startup code, there i wrote:
.section .reset,"ax",@progbits
.set noreorder
.ent _reset
_reset:
la $k0, _startup
jr $k0 # Jump to startup code
nop
.end _reset
.globl _reset
this worked perfect, now the linker uses the address of the _reset
procedure in the correct memory area as the startup address.
So is there a way I can get this behaviour in inline assembler?
Something like:
procedure reset; assembler; nostackframe; public name '_reset'; section
'.reset,"ax",@progbits';
???
TnX,
Michael
---- generated assemblerfile:
.section .text.n_pic32mx1xxfxxxb_$$_reset
.balign 4
.globl PIC32MX1XXFXXXB_$$_RESET
.type PIC32MX1XXFXXXB_$$_RESET,@function
PIC32MX1XXFXXXB_$$_RESET:
.globl _reset
.type _reset,@function
_reset:
.ent PIC32MX1XXFXXXB_$$_RESET
.section .reset,"ax",@progbits
la $k0, _startup
jr $k0
nop
.section .text.n_pic32mx1xxfxxxb_$$_reset
# path: mipsel/
# file: pic32mx_start.inc
# indx: 2
.Ll3:
jr $ra
nop
.set macro
.set reorder
.end PIC32MX1XXFXXXB_$$_RESET
.Lt2:
.Le1:
.size PIC32MX1XXFXXXB_$$_RESET, .Le1 - PIC32MX1XXFXXXB_$$_RESET
.Ll4:
Am 03.06.13 08:07, schrieb Michael Ring:
This version worked,
thank you for your help!
Michael
Am 02.06.13 23:20, schrieb Jeppe Græsdal Johansen:
Den 02-06-2013 23:15, Michael Ring skrev:
Unfortunately that does not seem to work (or I use it wrong):
This procedure:
procedure _general_exception_handler; assembler; nostackframe;
public name '_GENERAL_EXCEPTION_HANDLER';
asm
.section "reset"
sdbbp 0;
.Lloopb:
b .Lloopb
end;
translates to:
.section .text.n_pic32mx1xxfxxxc_$$__general_exception_handler
.balign 4
.globl PIC32MX1XXFXXXC_$$__GENERAL_EXCEPTION_HANDLER
.type PIC32MX1XXFXXXC_$$__GENERAL_EXCEPTION_HANDLER,@function
PIC32MX1XXFXXXC_$$__GENERAL_EXCEPTION_HANDLER:
.globl _GENERAL_EXCEPTION_HANDLER
.type _GENERAL_EXCEPTION_HANDLER,@function
_GENERAL_EXCEPTION_HANDLER:
.ent PIC32MX1XXFXXXC_$$__GENERAL_EXCEPTION_HANDLER
.section reset
sdbbp 0
.Lj11:
b .Lj11
jr $ra
nop
.set macro
.set reorder
.end PIC32MX1XXFXXXC_$$__GENERAL_EXCEPTION_HANDLER
.Lt3:
.Le2:
.size PIC32MX1XXFXXXC_$$__GENERAL_EXCEPTION_HANDLER, .Le2 -
PIC32MX1XXFXXXC_$$__GENERAL_EXCEPTION_HANDLER
.Ll8:
which creates an assembler error:
/Users/ring/devel/fpc/rtl/units/mipsel-embedded/pic32mx1xxfxxxc.s:94: Error:
operation combines symbols in different segments
the error is from the .size line.
Am 02.06.13 22:51, schrieb Jeppe Græsdal Johansen:
Den 02-06-2013 22:41, Michael Ring skrev:
Hi, perhaps I am overseeing a simple solution for my problem:
On the pic32 there are two flash areas, one at 0x9d000000 for the
main program and another at 0xbfc00000 that is called Boot Flash.
On reset the program starts in the boot flash at the first address.
I have written the startup code for the chips now but I need to
distribute some procedures between the two memory areas, for
obvious reasons I must have some code at address 0xbfc00000 or the
chip will not boot correctly ;-).
My thought was now to tweak the linker script in the same way the
original linker scripts of pic32 work:
MEMORY
{
kseg0_program_mem (rx) : ORIGIN = 0x9D000000, LENGTH = 0x80000
kseg1_boot_mem : ORIGIN = 0xBFC00000, LENGTH = 0x490
}
SECTIONS
{
.reset _RESET_ADDR :
{
KEEP(*(.reset))
KEEP(*(.reset.startup))
} > kseg1_boot_mem
}
In assembler I can then simply write:
.section .reset,code and
.section .reset.startup,code
and then the code, this will automagically end up in the
kseg1_boot_mem, but this does not work with the inline assembler.
Any ideas on how to do this the correct way? Is there something
more intelligent than to write a plain assembler file?
TnX,
Michael
You should be able to use
.section ".reset"
Try
procedure _general_exception_handler; assembler; nostackframe; public
name '_GENERAL_EXCEPTION_HANDLER';
asm
.section "reset"
sdbbp 0;
.Lloopb:
b .Lloopb
.text
end;
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