[syslinux] USB key: CBIOS line printed, nothing else

H. Peter Anvin hpa at zytor.com
Wed Sep 6 17:31:14 PDT 2006

Josh Lehan wrote:
> Rory Vieira wrote:
>> My own system has three: USB-FDD, USB-ZIP and USB-HDD.
>> The first is definatly different to the others when I'm using my usb key...
>> On my test system I have NO options at all, but I can clearly see it's
>> being used as a floppy.
> Nice.  There's a lot of differences between floppies and "fixed disks", 
> in the BIOS.  Among other things, the device number is 0x00 instead of 
> 0x80,

... true (for the first device of each type) ...

> and there's a different API for accessing it.

Not really true.  The geometry query function returns potential C/H/S 
instead of actual C/H/S for (legacy) floppy disks, which is a problem.

> In USB-FDD mode, the BIOS might also expect the USB key to be in superfloppy format (no 
> partition table or MBR, just one big filesystem across the entire disk 
> surface).

The BIOS shouldn't give a hoot.

> On this particular machine, my BIOS just gives me the choice between 
> USB-ZIP and USB-HDD.  On 3 other systems I have access to, 2 of them 
> don't give me any choice of USB modes at all, but they all do recognize 
> the USB key and let me choose it as a bootable choice, and work fine. 
> The third system doesn't support USB booting at all :(
>> My apologies for not being clear... all systems I have used my key on,
>> show EBIOS... again, my excuses for the mishaps
> I'm guessing USB booting support in this particular BIOS that fails to 
> boot, is half-baked.  It shows CBIOS.  As for the others, they flash by 
> too fast for me to see if they are CBIOS or EBIOS....

You should be able to press Ctrl-V at the command line and get the 
banner line again.


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