[syslinux] After USB boot problems on Gigabyte GA-M55Plus-S3G

[H. Peter Anvin]

On 01/22/2014 02:57 PM, Ronald F. Guilmette wrote:
> 
>> Could you please exercise what is described for Linux in
>>  http://www.syslinux.org/doc/usbkey.txt
>> and check whether
>>  mkdiskimage -4 /dev/sda 0 64 32
>> prepares a problematic stick for a normal installation of
>> Clonezilla, which then boots ?
> 
> I'm not sure if such a test will be useful.  Quoting the document in
> question:
> 
>      Some BIOSes have been reported (in particular, certain versions of
>      the Award BIOS) that cannot boot USB keys in "USB-HDD" mode.
> 
> this is quite clearly *not* a problem that either I or my BIOS have.
> Thus, I must ask, do you still want me to attempt this test?
> 
> If your answer is "yes", then you are going to have to help me in a couple
> of ways, specifically:
> 
>     *)  Your method of calculating number of cylinders, although explained,
>         is still just slightly opaque.  Can you elaborate a bit more?  I
>         do not get where the "(64*32)" part is comming from.  That seems
>         like the magician (you) just simply pulled that out of... a hat.
>         Is the divisor *always* exactly 2048, i.e. 64*32 in all cases, for
>         all USB drives in all systems?
> 

No.  The 64x32 happens to be the numbers used by the Iomega Zip drive,
and a lot of early USB BIOS support code was really written for
zipdrives more than for hard drives, which weren't commonly available in
the USB flavor back then.

As such, 64x32 seems to be the numbers that work best on some number of
systems, followed by 255x63 which are simply the largest possible
numbers and thus very commonly used for actual hard disks.

	-hpa