BIOS Flashing with a Bootable CD-ROM

• Submitted by: Kurt Wall
• Update by: Kurt Wall
• Date Submitted: 3 Jan 2006
• Last Updated: 14 Jan 2007
• Document Version: 1.2

I wanted to update the BIOS on my computer but faced a problem: no floppy drive and no DOS or Windows. Most BIOS flashing programs require either a floppy or DOS/Windows or both because the flashing programs run from DOS (Uniflash is a notable exception). Fortunately, smarter people than me worked out the details. Here are the steps, which presume you have boot-capable CD-ROM.

1. Create a directory in which to work. I'll refer to it as $WORKDIR in this document:

   $ mkdir $WORKDIR
   $ cd $WORKDIR
   

2. Download your updated BIOS image into $WORKDIR.
3. Obtain a DOS boot image — you can probably use one from the FreeDOS project, but I ended up using one from bootdisk.com, boot98sc.exe. Save or copy this file into $WORKDIR.
4. boot98sc.exe is a self-extracting ZIP archive, so unzip it into $WORKDIR:

   $ unzip boot98sc.exe
   Archive:  boot98sc.exe
   warning [boot98sc.exe]:  105508 extra bytes at beginning or within zipfile
     (attempting to process anyway)
   file #1:  bad zipfile offset (local header sig):  211016
     (attempting to re-compensate)
     inflating: boot98sc.IMA
   

   As you can see in the output, in this case, the bootable image is boot98sc.IMA.

5. Mount the bootable image using the loopback device:

   # mount -t vfat boot98sc.IMA /mnt/temp -o loop,rw
   

   You will need to be root to mount the image and you will also need to make sure that your mount point (/mnt/temp, in this case) exists.

6. Delete enough unneeded .exe files from the image to make room in the image for your BIOS update file and flashing program. The bootable image has a fixed size, 1,474,560 bytes, which is precisely the size of a floppy disk. However, while the image is that size, the files it contains do not necessarily use all of that space:

   $ du -b /mnt/temp
   1453799 .
   

   So, the trick is to figure out how much space you need and delete enough non-essential files from the image to make room for your BIOS image and the flashing program. In my case, the required space was approximately 570,000 bytes:

   -rw-r--r--  1 kwall users  46414 2006-01-02 23:34 awflash.exe
   -rw-r--r--  1 kwall users 524288 2006-01-02 23:31 w7093ae7.405
   

   So, I deleted the following files:

   • scanreg.exe
   • scandisk.*
   • extract.exe
   • edit.*
   • drvspace.bin
   • fdisk.exe
   • format.com
   • smartdrv.exe
   • xcopy32.*
   • mem.exe
   • chkdsk.exe
   • move.exe
   • deltree.exe

7. Copy your BIOS update file and flashing program into the mounted boot image:

   # cp awflash.exe w7093ae7.405 /mnt/temp
   

8. Unmount the boot image:

   # umount /mnt/temp
   

9. Create a bootable ISO image. Thus:

   $ cd $WORKDIR
   $ mkisofs -o bootcd.iso \
   > -b boot.IMA \
   > -c boot.cat \
   > ./boot.IMA
   

   • -o bootcd.iso tells mkisofs the name of the ISO image.
   • -b boot.IMA tells mkisofs where to find the bootable image to use.
   • -c boot.cat tells mkisofs the name of the boot catalog file that a bootable CD-ROM must have (you don't have to create it because mkisofs creates it for you).
   • ./boot.IMA tells mkisofs what files to put in the ISO.
10. Burn the ISO image using your preferred burning application.
11. Boot from the CD-ROM and run the flashing program according to the maker's instructions.

Additional Resources

As mentioned at the beginning of this document, I relied on the work other people did before. I've merged and synthesized elements from the pages listed below:

• Reflashing BIOSes from Linux
• Flashing PC BIOS under Unix/Linux in Non-Traumatic Fasion (with a CD-ROM or Floppy)
• Motherboard Flash Boot CD from Linux Mini HOWTO