Date: Fri, 9 Mar 2001 10:51:52 +0000 From: Josef Karthauser <joe@tao.org.uk> To: Luigi Rizzo <luigi@info.iet.unipi.it> Cc: hackers@freebsd.org Subject: Re: howto access an oddly shaped partition on a floppy ? Message-ID: <20010309105151.B40040@tao.org.uk> In-Reply-To: <200103091042.LAA48528@info.iet.unipi.it>; from luigi@info.iet.unipi.it on Fri, Mar 09, 2001 at 11:42:13AM %2B0100 References: <200103091042.LAA48528@info.iet.unipi.it>
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--ADZbWkCsHQ7r3kzd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Mar 09, 2001 at 11:42:13AM +0100, Luigi Rizzo wrote: > Hi, > i have the following problem (related to picobsd this is > why this msg is Bcc to -small). >=20 > We can format 1722KB floppies, which is 21 sectors/2heads/82 tracks, > but the bios is unable to boot from them -- it will only read > the first 18 sectors of each track and in many cases it will be > able to read all 82 tracks. >=20 > So one approach one would use with picobsd floppies could be the > following: format the disk with a 1722 format, but then put > a regular filesystem only on the "rectangular" area made > of 18 sectors/82 tracks. >=20 > It would be nice to access the rest of the disk (sectors 19-20-21 > of each track) as a separate volume. But how do we achieve this ? > One way could be to write some userspace program which knows > the mapping and reads/writes/seeks for you in the appropriate > places. Another one would be to modify the "fd" driver (apparently > you need to touch a couple of places in sys/isa/fd.c:fdstate() ) > to do the remapping for you, maybe driven by some table or sysctl > variable. The latter method would be more flexible as you would What about having the first few tracks, ie. the boot area, 18 sectors, and the rest of the disk 21 sectors, and have the boot code/kernel do the right thing? Isn't this easier? Joe --ADZbWkCsHQ7r3kzd Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (FreeBSD) Comment: For info see http://www.gnupg.org iEYEARECAAYFAjqotccACgkQXVIcjOaxUBYdGwCeO2+loAB35hrj7hSyIJgF7T5q FjsAoIIdAWUyzwIvxaEcbptsqtFcoGSj =f2Yj -----END PGP SIGNATURE----- --ADZbWkCsHQ7r3kzd-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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