Date: Thu, 31 Jul 1997 19:49:47 -0400 From: Matt Thomas <matt@3am-software.com> To: Terry Lambert <terry@lambert.org> Cc: freebsd-current@freefall.FreeBSD.org Subject: Re: core group topics Message-ID: <3.0.3.32.19970731194947.030b5044@ranier.altavista-software.com> In-Reply-To: <199707312022.NAA07684@phaeton.artisoft.com> References: <199707311142.EAA28471@implode.root.com>
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At 01:22 PM 7/31/97 -0700, Terry Lambert wrote: >> >Are we getting the kernel & userland mixed up here ? I belive there >> >is strong agreement for ELF for the kernel... >> >> There is? I don't recall discussing that at all, and if we do eventually go >> the ELF way, I think the kernel would be one of the last areas we'd want to >> convert since it further complicates our cramped bootblocks. > >This is only true if you maintain support for booting non-ELF kernels; >I view this as more of a transition issue than anything else. > > >> The only issue I have against ELF is that I'm concerned that the overhead >> for processing the much more sophisticated header at exec time might have a >> serious impact on exec performance (something I'm particularly sensitive to >> since I wrote the a.out exec code for FreeBSD). > >This is a bvery good point. But I think the benefits outweigh the >costs. In particualr, the kernel could map the ld.so instead of >making the crt0.o do it; this would buy back some of the overhead >right away, if it stayed mapped in the cloned porcess address space >from the fork to the exec. The same is actually true of the libc.so >and other shared libraries, albiet a bit of an arbitrary mapping >stretch (ie: pick a high address and map down). Specifically, I'd >only place libc in this boat, seeing as how few programs can exist >without system calls of one kind or another. That's how NetBSD does it. It loads the executable and the interpt. (ld-elf.so) and transfers controls to the interpt instead of the executable. -- Matt Thomas Internet: matt@3am-software.com 3am Software Foundry WWW URL: http://www.3am-software.com/bio/matt.html Nashua, NH Disclaimer: I disavow all knowledge of this message
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