Return to BSD News archive
Received: by minnie.vk1xwt.ampr.org with NNTP id AA262 ; Sun, 31 Jan 93 14:00:15 EST Path: sserve!manuel.anu.edu.au!munnari.oz.au!hp9000.csc.cuhk.hk!saimiri.primate.wisc.edu!zazen!decwrl!atha!sgiblab!spool.mu.edu!olivea!charnel!sifon!broue!captain From: captain@rot.qc.ca (Andrew Webster) Newsgroups: comp.unix.bsd Subject: Re: [386BSD] boot disk does absolutely nothing on gateway 4dx33v Message-ID: <C1LKFw.DLt@rot.qc.ca> Date: 29 Jan 93 03:59:55 GMT References: <1993Jan21.221451.10039@fcom.cc.utah.edu> Organization: Groupe de Recherche Operationnelle en Telecommunication (ROT) Inc. Lines: 62 X-Newsreader: TIN [version 1.1 PL8] A Wizard of Earth C (terry@cs.weber.edu) wrote: > In article <1jkdpeINNkeg@cat.cis.Brown.EDU> tim@news.Brown.EDU (Timothy Miller) writes: > >I have acquired the boot disk image for 386bsd, and no matter what I try, > >when my system starts up, it displays all the bios messages, and then hangs [stuff deleted]... > This is the "Compaq boot problem". You can get the patch from the file > ~/terry/patch.bootblock.fdboot.c on ref.tfs.com, download a Compaq > dist.fs or fixit,fs, or go to a news archive and get the article > "Message-ID: <1992Dec08.132820.29435@crash>". > The problem is insidious, and it's a wonder anyone can boot at all; from > the referenced article: > ] Also, Akihiro Higashi, in article > ] <1992Sep11.051554.29192@mlab.nttdocomo.co.jp>, reported that he > ] had to change 3rd & 4th "NOP"s to "JMP .+2"s on his COMPAQ 486/50L. > ] 'NOP' is a delay macro which alters the AL register. The specific > ] ange 3rd & 4th "NOP"s to "JMP .+2"s on his COMPAQ 486/50L. > ] 'NOP' is a delay macro which alters the AL register. The specific > ] instances mentioned involve code resetting the DMA controller's first/last > ] flip-flop and then programming the DMA controller's mode register. > ] The initialization byte for the mode register is clobbered by a NOP > ] (I am amazed that the boot works on most systems!). This can be fixed > ] by rearranging the code slightly. > And for brave, brave souls: > ] Fortunately, these changes do not shift the boot code, so a binary patch > ] is possible. The changes to the first sector on the disk (fixit.fs or > ] dist.fs) are given below: > ] > ] Offset Old New > ] ------ ---- ---- > ] 0x00e1 0x07 0xbf > ] 0x00f2 0xb0 0xee > ] 0x00f3 0x46 0xe4 > ] 0x00f4 0xee 0x84 > ] 0x00f5 0xe4 0x4a > ] 0x00f6 0x84 0xb0 > ] 0x00f7 0x4a 0x46 > I believe the pattern "b0 46 ee e4 84 4a" would exist even on altered boot > disks, since this portion of the boot would be unchanged, even if not at > the same offset. Work back by -15 (decimal) to fix the e1 offset value. > Using either a binary patch or Compaq boot disks should alleviate the > need to have a working system to build a disk to have a working system... I tried the binary patch, and lo-and behold it boots! Thanks! ------------------------------------------------------------------------------- captain@broue.rot.qc.ca | Andrew Webster | "The engines canna take it | | anymore cap'n..." IP: 192.77.49.131 | ROT inc. ------------------------------ | Recherche Operationnelle en Telecommunication | Voice: +1 514 737 0020 | Dataradio Inc. Fax: +1 514 737 7883 | Montreal, Quebec -------------------------------------------------------------------------------