Date: Tue, 07 May 2002 14:58:48 -0400 From: Nathan Hawkins <utsl@quic.net> To: arch@FreeBSD.ORG Subject: Re: syscall changes to deal with 32->64 changes. Message-ID: <3CD823E8.2010809@quic.net> References: <XFMail.20020507103320.jhb@FreeBSD.org> <3CD7FE57.1000508@quic.net> <20020507110901.F23330@dragon.nuxi.com>
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David O'Brien wrote:
>On Tue, May 07, 2002 at 12:18:31PM -0400, Nathan Hawkins wrote:
>
>
>>I'd like to see FreeBSD start using ELF .note.ABI-tag sections to handle
>>the binary OS type/versioning. I know that at least NetBSD, Linux and
>>Hurd do it this way, and I think most others do too.
>>
>>
>
>Why? Just to follow the NIH herd? The EI_OSABI and EI_ABIVERSION fields
>were in the gABI spec before anyone started using .note sections for
>this.
>
>
Because AFAICS, it's a defacto, unwritten standard. Even if it violates
spec.
NIH is a matter of perspective. FreeBSD could be considered to be in NIH
mode, because the other ELF based systems use a different method.
>If .note.ABI-tag is the end all and be all, then why did the ELF spec
>authors even create EI_OSABI and EI_ABIVERSION?? And why did they put
>things in the ELF header such that things are very easy to parse just by
>reading a small amount of a binary? A LOT of the things in an ELF header
>could have been put in .note sections. But they weren't because it is so
>much easier to read fixed structures.
>
I have no axe to grind here. I don't consider the .note.ABI-tag to be a
beautiful way to do things. You're right, it should be faster to get
this from a field in the ELF header. But you also use the .interp
section in the emulation selector code. I think that the .note.ABI-tag
would be a better choice.
>That said, run readelf on any FreeBSD binary, you will find a
>.note.ABI-tag section. I just never got around to adding support for it
>to imgact_elf.
>
Yes, I can see that. I've looked at adding support to imgact_elf. I
haven't had time to try yet.
---Nathan
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