Date: Mon, 14 Apr 2003 10:36:55 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: Toerless Eckert <eckert@i4.informatik.uni-erlangen.de> Cc: freebsd-hackers@FreeBSD.org Subject: Re: boot2 broken ? (booting from pst fails) Message-ID: <XFMail.20030414103655.jhb@FreeBSD.org> In-Reply-To: <200304112357.BAA02170@faui40p.informatik.uni-erlangen.de>
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On 11-Apr-2003 Toerless Eckert wrote: >> > - Q: Is btx actually switching to real mode for int 13 ? Could it be >> > that there's a bug in that code ? >> >> No, we run it in virtual 86 mode, and it is likely that their BIOS >> routine just can't handle that. >> >> > - Q: Are there any alternatives how i could boot a 4.8 or 5.0 freebsd >> > solely from the disk ? (I guess i could try to install a linux and >> > then use liloboot, but that also uses the btx code from loader...) >> >> Nope. :( Other than get promise to fix their BIOS maybe. > > - Why is the BIOS routine not run in real mode ? Would it be hard trying > to change BTX so that it executes the interrupt in real mode ? Yes. Not to mention lack of space in boot2 for BTX to grow to support this. > - Is there actually a requirement for a BIOS to work correctly > in virtual mode ? I was under the assumption that BIOS is always > only assumed to need to work correctly in real mode. If this is > not true, then i would welcome if you could point me to an official > PC98, .. (or whatever) document WIntel , or > whoever leads the conspiracy what officially are requirements for a "PC"). > > Without such a reference i think anybody would have a hard time arguing > the case of requesting support for virtual mode from the BIOS of some > HW vendor, right ? Basically, the only problems we have with BIOS's usually happen because the BIOS writer thought they could be cute by entering protected mode themselves instead of using the defined BIOS calls (such as int 0x15, function 0x87) to access upper memory, etc. > - Do you know wether Linux relies on virtual mode in booting their kernel ? > because the vendor in my case is officially suporting linux. I guess i > need to test setting that up and see if i can boot it from the disk. Linux doesn't have a bootloader like FreeBSD. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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