include/asm-mips/elf.h contains a macro, elf_check_arch, that decides if an
executable is plausible to run under this kernel. It currently accepts
binaries flagged as MIPS1 ISA, and rejects all other ISAs.
#define elf_check_arch(hdr) \
int __res = 1; \
struct elfhdr *__h = (hdr); \
if ((__h->e_machine != EM_MIPS) && \
(__h->e_machine != EM_MIPS_RS4_BE)) \
__res = 0; \
if (__h->e_flags & EF_MIPS_ARCH) \
__res = 0; \
I think we should make an exception for MIPS2. Turns out that the two Linux
VR processor families benefit from some of the MIPS II features; most
notably, code density is improved by eliminating load delay slots. If I
build executables that take advantage of this, they legitimately should be
flagged with E_MIPS_ARCH_2 (since they won't run on my decstation).
So what's the right way to fix this? Three things come to mind:
1) rip out the EF_MIPS_ARCH check from elf_check_arch.
2) compare the value with E_MIPS_ARCH_1 and E_MIPS_ARCH_2
3) figure out what the capabilities of the current processor are and reject
E_MIPS_ARCH2 on R2/3000s.
I'd just go do #3 except it looks like a bigger pain than it's worth. No
other linux kernel port goes to that amount of trouble, of course.
(I may do #1 or #2 in the Linux VR CVS as a stopgap.)