Installing several OSes from a single flash drive
I've been tinkering with the idea of installing different operating
systems, not necessarily Linux, from the same bootable flash drive. What
I came up with was an extension of Miron's guide[1] on making a writable
bootable flash installer. It turns out that the syntax for the
syslinux.cfg file is the same as is used with PXELINUX. Therefore, the
recipies I already have for PXE booting can be easily translated to flash
booting. Here's an example syslinux.cfg file from my preliminary
writeup[2]:
===begin quote===
ui menu.c32
prompt 0
menu title My Flash Drive Installer
timeout 0
label amd64
menu label Install Debian 7.3.0 (Wheezy) amd64
kernel amd64/linux
append initrd=amd64/initrd.gz auto file=/hd-media/preseed.cfg
lang=en_US.UTF-8 locale=en_US
quiet
label i386
menu label Install Debian 7.3.0 (Wheezy) i386
kernel i386/linux
append initrd=i386/initrd.gz auto file=/hd-media/preseed.cfg
lang=en_US.UTF-8 locale=en_US
quiet
label memtest
menu label Memtest86+ 5.01
kernel memtest86+-5.01
===end quote===
Adding to this, I like to have a skeleton home directory on the flash
drive with things set up the way I like them. Because SYSLINUX works only
on FAT filesystems, I use EXTLINUX to make a bootable ext2 or ext3
filesystem so the permissions aren't mangled. This approach works just
the same as above except you put the config in extlinux.conf instead of
syslinux.cfg. There are also some differences in the invocation of
EXTLINUX compared to SYSLINUX.
This tinkering exposed a problem with Debian's hd-install boot images.
As is pointed out in Miron's article, an hd-install image will check the
boot media for a Debian ISO from which to draw packages. There is a flaw
in the implementation in that the installer will mount EVERY ISO it finds
to the same mount point. If you try to include seperate ISOs for amd64
and i386, you can't tell which ISO will actually be visible to the
installer. The first symptom of this is that the installer complainst
that it cannot find any suitable kernel packages.
Would someone please point me to the section of code that is responsible
for mounting the ISOs so I can fix this? Mounting every ISO on the flash
drive shouldn't be bad as long as the installer can check each of them in
turn.
I suppose another solution would be to have an ISO composed of the
contents of both the amd64 CD and i386 CD. Does anyone have any advice on
generating such an ISO?
[1] http://hyper.to/blog/link/debian-installer-on-a-usb-key
[2] http://661.org/articles/flashinstall.html
--
David Griffith
dave@661.org
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