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USB stick boot (mission impossible Ⅱ)

01.01.2009 by tg@
Tags: bug grml hardware

After my earlier escapades, which you might have read about, here’s some news regarding USB sticks:

  • The IBM X40 can boot, but always uses a geometry of LBA translated into 255 heads, 63 sectors per track, contrary to the “USB ZIP” one which demands 64 heads, 32 sectors per track.
  • The ALIX.1c does recognise the stick’s physical or USB ZIP geometry, since they match each other and what the BSD kernel thinks:
    sd0: 241MB, 241 cyl, 64 head, 32 sec, 512 bytes/sec, 495607 sec total
    However, it still cannot boot MS-DOS® 7.10 from the stick. WTF?
  • The VIA C7 can still not boot from the stick. It doesn’t even appear in the boot menu. Interestingly enough, it does try to boot from SCSI even if unlisted (disabling the AHA-2940U2B BIOS helps to disable it, but I don’t even know where that MBR code which it did boot came from…)
  • I still hate ATX. I fragged a K6-2 mainboard when trying to power it on due to a flash(?) (German: Überschlagsblitz). Also, I definitively have a lack of hardware with an ISA slot, a floppy drive, and USB.
  • The (old) herc hardware might work, but its keyboard controller is damaged, ISTR I wrote about it ages ago. Some day, I’ll either solder in a new one or use a USB keyboard to bring it back working (to hack a hercules framebugger).

So the way out of this misére is a “machine sector <type> <filename>” command for boot(8/i386). It should be able, at least, to load: an MBR/PBR, a GNU GRUB stage2, stage2_eltorito (with boot-info-table emulation), SYSLINUX, ISOLINUX, EXTLINUX, an MS-DOS® 7.x IO.SYS. But at the beginning, I’m content with less. Because it seems to be impossible to boot DOS from a USB stick, due to the varying CHS geometries, MEMDISK might be the way to go for a triple-boot stick. A combined grml+MirBSD thing would not be hindered by it because both SYSLINUX and boot(8/i386) use the LBA access method if available.

Benny beat me, he did the first commit this year. Congrats! Oh, and the second and the third. But I’ll write the first wlog entry, hahaha, and the Developers’ Weblog is not a blog! Oh, and the fourth.

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