Wanted to flash a BIOS lately and noticed that all major mainboard manufactors still use DOS flash utilities? I did. Unfortunately my mainboard isn’t supported by flashrom yet and a floppy drive wasn’t available. So, why not use FreeDOS?
1. Installing packages
Well, this one is rather easy. Just pull the packages from your yum-repo:
yum install xinetd tftp-server syslinux
2. Configuring xinetd
Enabling xinetd (and tftp) is no big deal:
chkconfig xinetd on chkconfig tftp on
You may want to find out (or adjust) the tftp root path. Simply edit
/etc/xinetd.d/tftp with your favourite editor and change the line that says
server_args = -s /tftpboot. Make sure, the service is restarted after you changed something in the configuration file.
3. Setting up boot environment
First, you have to copy the pxelinux kernel and memdisk to your tftp directory. Assuming that your tftp root is
/tftpboot (note that Fedora changed this default path in Fedora 9):
cp /usr/lib/syslinux/pxelinux.0 /tftpboot/ cp /usr/lib/syslinux/memdisk /tftpboot/
Second, we create the
pxelinux.cfg directory and a default configuration file
mkdir -p /tftpboot/pxelinux.cfg/ touch /tftpboot/pxelinux.cfg/default cat >> /tftpboot/pxelinux.cfg/default <<EOF default dos label dos kernel memdisk append initrd=fdboot.img EOF
And finally, we download the raw image of a minimal FreeDOS boot floppy (fdboot.img) from http://www.freedos.org/freedos/files/
wget http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/1.0/fdboot.img -O /tftpboot/fdboot.img
4. Manipulating the image
Now we can boot into FreeDOS. But how do we flash the motherboard BIOS? Simply include the BIOS ROM file and the flash utility from your mainboard manufactor into the FreeDOS boot image:
mount -t vfat -o loop fdboot.img /mnt/floppy
Copy every file you need for flashing your BIOS (or doing other bullshit) to
/mnt/floppy. Don’t forget to unmount the image before you boot via PXE.