Date: Mon, 06 Dec 2010 19:40:01 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: Tijl Coosemans <tijl@coosemans.org> Cc: svn-src-projects@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r216200 - in projects/binutils-2.17: contrib/binutils/bfd contrib/binutils/gas/config contrib/binutils/ld/emulparams gnu/usr.bin/binutils/libbfd sys/boot/ia64/efi sys/boot/ia64/ski sys/... Message-ID: <4CFD2E01.1000509@FreeBSD.org> In-Reply-To: <201012061718.13823.tijl@coosemans.org> References: <201012052024.oB5KOMUF007051@svn.freebsd.org> <201012061718.13823.tijl@coosemans.org>
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On 2010-12-06 17:18, Tijl Coosemans wrote: > On Sunday 05 December 2010 21:24:22 Dimitry Andric wrote: ... >> For ia64, add a proper 'elf64-ia64-freebsd' output format to BFD, so the >> ELF branding for FreeBSD is done in the same way as amd64, i386 and >> sparc. Something similar should probably also be done for arm, mips and >> powerpc. ... > Does this change fix the problem described here? > http://lists.freebsd.org/pipermail/freebsd-ia64/2010-November/002773.html That problem is most likely due to using the binutils 2.20.1 port, which does not have support for a FreeBSD/ia64 target. I posted a similar patch for binutils 2.20 (without any base system modifications) here: http://lists.freebsd.org/pipermail/freebsd-current/2010-December/021649.html > About elf64-ia64-freebsd, I'm not sure it is needed. FreeBSD 4.0 and > older used non-standard ELF branding and that format got the name > elf32-i386-freebsd (and elf64-alpha-freebsd). Later versions of FreeBSD > use the standard method, but keep calling it elf32-i386-freebsd. The problem is that BFD needs to set the ELF_OSABI field in the ELF header to ELFOSABI_FREEBSD, at least for FreeBSD targets (whereas Linux does not care about the ELF_OSABI field at all, it seems). Because BFD sets the ELF_OSABI field to ELFOSABI_SYSV by default, this can only be done properly by selecting a specific BFD target ("elf64-ia64-freebsd") which is different from the default, usually "elf64-ia64-little". The same principle applies to other arches. In our base binutils, there is a hack in contrib/binutils/bfd/elf.c (function prep_headers(), line 4325) to set that field unconditionally, but obviously this is not in upstream binutils, as it would most likely be unacceptable for them. (Just maybe, if it was put between #ifdef __FreeBSD__ guards, but still unlikely. :) (Note that due to this elf.c hack, the messing with elf-fbsd-brand.c in gnu/usr.bin/binutils/libbfd/Makefile.{amd64,ia64} is actually completely unnecessary...) > Rather than copying this practise to other architectures, maybe > binutils should be fixed for i386. It isn't used on amd64 and sparc64 > either as far as I can tell. It is, in the binutils-2.17 branch, which has . :) The question is if we want to propagate our elf.c hack forever, in which case it would have to be added to the binutils port. The alternative, adding FreeBSD-specific targets, is more likely to be accepted by the binutils maintainers, which would be nice if we want to be able to build with "stock" binutils on FreeBSD. I am completely open for both approaches, really, and would like to see a bit of consensus. The "just hack elf.c" approach causes less churn in the tree, because it is small, and saves modifying a few places in the tree where target names are used, such as kernel link scripts. There is no way to specify a "non-FreeBSD" target, though. The "add FreeBSD targets" approach causes a bit of churn, but if we submit the required changes to binutils upstream, they are more likely to be accepted, as they are fairly minimal, and don't disturb support for other platforms. There will also be the possibility to produce non-FreeBSD-branded ELF files, although I am not sure if that is used very often. So, which colour? :)
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