Hello, I'm having problems mixing MIPS 32-bit object files compiled with two different compilers. 1) gcc version 4.4.1 (Sourcery G++ Lite 4.4-305) 2) Green Hills Software (exact version unknown) Before describing my problem, I'd like to ask a few questions. GCC supports several MIPS ABIs. Where are they documented? http://gcc.gnu.org/onlinedocs/gcc/MIPS-Options.html -mabi=32 -mabi=o64 -mabi=n32 -mabi=64 -mabi=eabi ( Links for self reference ) http://gcc.gnu.org/gcc-3.4/mips-abi.html http://www.cygwin.com/ml/binutils/2003-06/msg00436.html http://math-atlas.sourceforge.net/devel/assembly/mipsabi32.pdf Next question, when a function starts, is the stack pointer (r29) supposed to point to A) the last live value in the previous frame OR B) the first free/available word in the current frame ??? Do different compilers have different conventions/ABIs? The reason I ask is because, in my default invocation, gcc seems to consider case B: $ cat foo.c extern void bar(void *p); void foo(void *p) { bar(p); } $ mips-sde-elf-gcc -S foo.c .file 1 "foo.c" .section .mdebug.abi32 .previous .gnu_attribute 4, 1 .text .align 2 .globl foo .set nomips16 .set nomicromips .ent foo .type foo, @function foo: .frame $fp,24,$31 # vars= 0, regs= 2/0, args= 16, gp= 0 .mask 0xc0000000,-4 .fmask 0x00000000,0 .set noreorder .set nomacro addiu $sp,$sp,-24 sw $31,20($sp) sw $fp,16($sp) move $fp,$sp sw $4,24($fp) lw $4,24($fp) jal bar nop move $sp,$fp lw $31,20($sp) lw $fp,16($sp) addiu $sp,$sp,24 j $31 nop .set macro .set reorder .end foo .size foo, .-foo .ident "GCC: (Sourcery G++ Lite 4.4-305) 4.4.1" gcc stores r4 at fp+24 (fp+24 being the initial value of sp) But the other compiler seems to consider case A. _kernel_ini_system: addiu r29,r29,#-0x10 sw r31,0x0C(r29) sw r16,0x0(r29) or r16,r4,r0 sw r17,0x4(r29) ori r17,r0,#0x1 jal 0x80159CF4 lw r4,0x8(r16) The GHS compiler preserves the value pointed to by (the inital value of) sp. Is my understanding of the problem correct? If so, how do I make the two compilers agree on calling conventions? -- Regards.
