Date: Wed, 12 Jul 2000 11:21:27 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: cvs-all@FreeBSD.org, cvs-committers@FreeBSD.org Subject: RE: cvs commit: src/sys/boot/i386/boot0 Makefile boot0.s Message-ID: <XFMail.000712112127.jhb@FreeBSD.org> In-Reply-To: <200007121811.LAA81651@freefall.freebsd.org>
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On 12-Jul-00 John Baldwin wrote: > jhb 2000/07/12 11:11:55 PDT > > Modified files: > sys/boot/i386/boot0 Makefile boot0.s > Log: > The new and improved boot0, v1.1. This version adds the following: > - Autodetection and support of the BIOS EDD extensions to work around the > 1024 cylinder limit on all but really ancient BIOS's. > - To work around some BIOS's which break when EDD is used with older > drives, > we only attempt to use EDD if the cylinder is > 1023. > - Since this new code required more space than we had left, expand boot0 to > 2 sectors (1024 bytes) in length. > - Add support for boot0 being multiple sectors using predefined constants. > If boot0 needs to be extended in the future, all that is required is > bumping the NUM_SECTORS constant. > - Now that we have more room to work with, add a few more fs type > descriptions while making others more verbose. I hereby declare the 1024 cylinder limit dead. *stomp* *stomp* Actually, there still is a limitation in that if you have a really old BIOS without EDD support (pre-1995), you may still be limited to 1024 cylinders (528 meg w/o LBA translation, 8.4 gig with LBA translation). However, most such boxes are probably not dual-booting Windows and BSD. There is also the issue that if disk has a cylinder that is only 1 sector long, it won't be able to use the new boot0 unless the first partition starts on the second cylinder. The only disks known to suffer from this are small flash disks with geometries of 512/1/1 for example. However, I doubt that people are running multiple interactive OS's from a 256k disk. -- 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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