Date: Tue, 19 Sep 2000 18:50:55 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Robert Nordier <rnordier@nordier.com> Cc: Peter Wemm <peter@netplex.com.au>, mjacob@feral.com, Bruce Evans <bde@zeta.org.au>, Doug Rabson <dfr@nlsystems.com>, "Matthew N. Dodd" <mdodd@FreeBSD.org>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern subr_bus.c Message-ID: <XFMail.000919185055.jhb@FreeBSD.org> In-Reply-To: <200009200118.DAA11525@c3-dbn-96.dial-up.net>
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On 20-Sep-00 Robert Nordier wrote: > John Baldwin wrote: > >> On 20-Sep-00 Robert Nordier wrote: >> > Peter Wemm wrote: >> > >> >> Matthew Jacob wrote: >> >> > >> >> > I'll second this. >> >> >> >> Well, on the x86 we clear it twice, once in loader and once in locore. I >> >> thought it was redundant on the x86 since I thought the new boot2 cleared >> >> the extended ELF segment sizes. We do not support a.out kernels anymore >> >> so the old bootblocks are not an issue. (the old gas-1.9x cannot >> >> assemble >> >> the .s files). >> >> >> >> IMHO we should fix this bug in boot2. It costs ~32 bytes. (ie: reduces >> >> from 212 bytes free to 180 bytes free). >> > >> > If the bss clearing code is actually to be dropped from the x86 >> > kernel, I'd be happy for this to change. Otherwise 15% of available >> > space is a lot to spend for no actual benefit beyond a kind of >> > theoretical tidiness. >> >> Well, the loader needs its BSS cleared as well, so boot2 can't drop its >> BSS clearing code, AFAIK. > > The issue was adding bss clearing code to boot2, not removing it. Hmmm. We need to revamp the boot2 keyboard probe code to be more aggressive and actually poke at port 0x60 some like the kernel does so that it detects keyboards on broken Athlon motherboards properly. When I was playing with that, it took up all the free space in boot2 to do so, and BTX has grown since then, so I doubt we will have room in boot2 for clearing BSS unless someone is really masochistic and wants to rewrite all of boot2 in real-mode assembly (so we don't need BTX) and maintain it that way. I'm not volunteering for such an evil task. >> Esp. if the loader switches to being an ELF >> binary, which it might in 5.0 current if some people have their way. > > The loader is already an ELF binary and already gets its bss cleared > (by btxldr). The btxld composite object is presently a.out, but > changing this to elf won't affect bss as btxld doesn't use bss. Argh, you're right. /me crawls back into his hole. > -- > Robert Nordier -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.cslab.vt.edu/~jobaldwi/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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