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[bug #17653] Sometimes (on some motherboards?) Flash Drives detected as
[bug #17653] Sometimes (on some motherboards?) Flash Drives detected as floppy disk (fd1). How I can get access to partitions?
Sat, 30 Dec 2006 09:36:38 +0000
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Follow-up Comment #4, bug #17653 (project grub):
On GRUB side it's interesting too. It's quite unfortunate situation: during
GRUB setup the device is seen as "HDD" while on boot BIOS presents it twisted
to a "floppy".
Syslinux uses same code for both so it doesn't matter there, however GRUB has
the special workaround at the very start: it remembers it was installed to
HDD, checks the device number, if it is not 80h or above, forces 80h.
So after printing "GRUB" it is trying to read not from boot device (flash,
presented by BIOS as (fd1)) but from (hd0) present on the system. Verified:
after unplugging internal HDD, the message when booting from flash drive
becomes "GRUB Hard Disk Error".
Ok, replaced the two NOPs (90 90) at offset 75 with original JMP (EB 07).
Another place where GRUB has wrong data is the start sector of stage2,
because this was counted from MBR, while now 0 begins at boot sector, 32
sectors closer .. corrected this, at offset 44.
Result: "GRUB Geom Error". Hmmm, not there yet.
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