Re: Dangerous course of action suggested by USB boot instructions?
Lennart Sorensen wrote:
If it is really slow, you might be running with sync mount, which is a
very very bad idea for flash memory.
My mistake, that's what I was doing. Thanks for the tip. :)
And if you don't write a boot block to the device what makes it
bootable? Unless USB booting is even more screwy that I thought (I have
ever bothered to try it), then it should still need a bootable device to
boot which would require something writing to the MBR of the device.
Yes: that's why, on the same page [1], the guide suggests doing:
# install-mbr /dev/sda
However, this doesn't work (tested on two different laptops from
different manufacturers): the BIOS saw the stick and tried to boot, but
I only got something like the following output:
MBR
Boot error
Unfortunately, once you've done zcat boot.img > /dev/sda, your original
MBR is gone, so you can't even restore it. The user is now shafted. :)
What does work, however, is using the mbr.bin file contained in the
syslinux distribution (it's not included in the Debian package of
syslinux, not sure why):
# cat mbr.bin > /dev/sda
In any case, I would suggest that the instructions [1] be changed to
something like the following:
1. zcat boot.img > /dev/sda1
2. If the stick doesn't boot, cat mbr.bin > /dev/sda
In this way:
1. The stick's MBR is not going to be trashed and replaced by something
that doesn't work.
2. The user will still be able to see and access [the first 128 MB of]
the stick from Windows as well, and even reformat it to restore it to
its original capacity.
Cheers,
Lorenzo
[1] http://d-i.alioth.debian.org/manual/en.i386/ch04s04.html
--
Lorenzo Colitti http://www.colitti.com/lorenzo/
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