Date: Thu, 02 Mar 2000 20:46:01 -0500 From: Sergey Babkin <babkin@bellatlantic.net> To: Christian.Gusenbauer@netway.at Cc: davidd@stack.nl, hackers@FreeBSD.ORG Subject: Re: FreeBSD-boot Message-ID: <38BF1959.881B5538@bellatlantic.net> References: <00030219400601.00224@bones.my.domain>
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Christian Gusenbauer wrote: > > Hi David! > > I'm sorry for you, but FBSDBOOT will never support ELF binaries :-(! As > developer of this utility I had a discussion about supporting ELF when ELF was > introduced into FreeBSD. The reason, why ELF support was not integrated is, that > the new boot loader and the kernel rely on the state of the hardware, BIOS > and BIOS extensions. Sorry for a stupid question but how was it able to boot with aout ? I think FBSDBOOT never worked after HIMEM.SYS and things like it were loaded, it always required a clear plain DOS to work. So maybe there is a chance that it can be adapted for ELF when started from a plain DOS ? > Since booting DOS modifies the lower memory and hardware settings (eg. sets > registers, or modifies interrupt vectors) this state will not exist, when you > start FBSDBOOT. FBSDBOOT itself *can not* restore this state and therefore > fails to start up the ELF binary (loader and/or kernel). How about loading the kernel starting at 1MB and leaving the memory under 1MB unused ? Then you won't even have to restore the interrupt vectors: as long as DOS is left in its place all the interrupts should not get broken. > Of course, there is a well known address in the BIOS, where the original > interrupt descriptor table is located, but restoring this table is not enough. > You also have to re-initialise the various devices (eg. Adaptec Controller). But I wonder why would you have to do that ? I guess this would be needed only after the ASPI driver was loaded. But if it was not then DOS just blindly calls the BIOS. And I guess for the boot code there shoul be no difference whether this is IDE BIOS or Adaptec BIOS. Well, maybe nowadays when the plain DOS is almost completely displaced by Windows 9x maybe future work on FBSDBOOT is not worth the effort in any case. -SB To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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