On Fri, Jun 28, 2013 at 7:38 PM, <tlaro...@polynum.com> wrote: > On Fri, Jun 28, 2013 at 12:40:46PM -0400, erik quanstrom wrote: > > > > this iso uses the traditional el-torito method. unfortunately, > > the installer is size-constrained (1.44MB) and doesn't support usb. > > > > FWIW (I implemented El-Torito support for GRUB years ago), the image has > to be some floppy size, and 2.88MB is perfectly supported. > > There is also hd emulation, but this it seems not to be widely > supported by BIOSes. > > There are various ways of booting with El-torito.
http://download.intel.com/support/motherboards/desktop/sb/specscdrom.pdf One of the ways is non-emulation (I thought it had appeared in a later version of El-torito, but checking the spec it was already in version 1, 1995), the byte 1 in page 19, description in page 16. Mkisofs lets you create a non-emulation bootable image (see /sys/src/cmd/disk/9660/boot.c:166, which is set with -B) or an emulation image. Emulation goes hand in hand with pbsraw.s. It used to be that many BIOSes did not support non-emu, but that has not been true AFAIK for a long while (at least more than 10 years). As long as you have the blocks 2M aligned you should be fine with most modern BIOSes. I think the problem is that the Plan 9 iso is somewhat different than k3b expects and it is "fixing" it, although as I said, the iso format is complex enough and has enough variants that there may be some error somewhere or the BIOS may have a bug... G.
