[syslinux] "Boot error" message

H. Peter Anvin hpa at zytor.com
Mon Jan 11 10:05:14 PST 2010

On 01/11/2010 08:49 AM, braiamserafim at terra.com.br wrote:
>  Hi,
>  I'm getting a "Boot error" message when the BIOS tries to boot a SPI
> flash disk. I installed the syslinux on SPI flash disk mounted as a
> block device. The flash was formatted as FAT12. The BIOS emulates the
> flash as floppy.
>  I also tried to install the bootloader using a DOS version of
> syslinux running on FreeDOS. If I use this way so the BIOS boots
> correctly.
>  Why am I getting that error message?

Because the geometry that the BIOS uses isn't the same as the one
written into the FAT12 superblock on the disk.  This is particularly
important for floppy-emulation devices because there is no reliable way
to query the geometry of a floppy device.

The reason the DOS installer works (it's probably actually the DOS
FORMAT program) is because since it is running under FreeDOS, it's using
the BIOS to write the disk, and thus it is using the same geometry.

H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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