Date: Wed, 10 Mar 2010 08:39:15 -0600 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-emulation@freebsd.org, freebsd-amd64@freebsd.org, freebsd-ia64@freebsd.org Subject: Re: Request for review/comments: 32-bit compat for non-x86 architectures Message-ID: <4B97AF13.5040104@freebsd.org> In-Reply-To: <201003100810.10696.jhb@freebsd.org> References: <4B971CA3.9090301@freebsd.org> <201003100810.10696.jhb@freebsd.org>
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John Baldwin wrote: > On Tuesday 09 March 2010 11:14:27 pm Nathan Whitehorn wrote: > >> The patch at http://people.freebsd.org/~nwhitehorn/compat_freebsd32.diff >> (pre-generated freebsd32 syscalls stuff is included, which will be done >> in two steps on commit) provides groundwork for supporting 32-bit >> compatibility for 64-bit MIPS and PowerPC systems. It has been tested on >> amd64 and powerpc64, and compile-tested on ia64. There are two main >> parts to the patch: >> >> 1) COMPAT_IA32 is renamed COMPAT_FREEBSD32, in analogy to >> COMPAT_LINUX32, etc. This requires updating kernel configurations, but >> is less painful than filling machine-independent bits of the kernel with >> #if defined(COMPAT_IA32) || defined(COMPAT_PPC32) || >> defined(COMPAT_MIPS32) || ..., and is no less descriptive than the old name. >> >> 2) Modifications to the freebsd32 compat layer to support big-endian >> architectures. >> >> I would appreciate any comments, bugs, or test results on ia64. >> > > This doesn't look right for non-x86 32-bit ABIs: > > Index: sys/kern/imgact_elf.c > =================================================================== > --- sys/kern/imgact_elf.c (revision 204681) > +++ sys/kern/imgact_elf.c (working copy) > @@ -1439,7 +1439,7 @@ > ehdr->e_ident[EI_ABIVERSION] = 0; > ehdr->e_ident[EI_PAD] = 0; > ehdr->e_type = ET_CORE; > -#if defined(COMPAT_IA32) && __ELF_WORD_SIZE == 32 > +#if defined(COMPAT_FREEBSD32) && __ELF_WORD_SIZE == 32 > ehdr->e_machine = EM_386; > #else > ehdr->e_machine = ELF_ARCH; > Good catch! Such are the dangers of sed. How about defining an ELF_ARCH32 in machine/elf.h for this case? > It would be nice to eliminate having <compat/ia32*> includes in MI code by > instead including those headers in appropriate headers in <machine/*>. For > example, we could change <machine/reg.h> on amd64 and ia64 to include these > headers, perhaps under an #ifdef COMPAT_FREEBSD32. > > Hmm, actually, I'm quite convinced now that <machine/reg.h> for ia64 and amd64 > should include <compat/ia32/ia32_reg.h> in the #ifdef _KERNEL section to avoid > polluting those includes in MI code. I'm not sure what the various > <machine/fpu.h> includes are for, but fixing ia32_reg.h would be a good first > step. It would make your diffs smaller I think. > This is how it works on powerpc64. I didn't modify amd64 and ia64 in order to avoid making too many changes, but I think you're right that this is a good idea. I'll add that to the patch when fixing the EM_386 bit you pointed out above. > The rest of the diff looks fine to me. > Thanks for the comments! -Nathan
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