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

[Ady]

> 
> Ady:
> > I also "forced" a FAT32 LBA filesystem,
> Ronald F. Guilmette:
> >     *) with respect to Ultimate Boot CD (5.2.7), the answer is "CHS".
> >     *) with respect to OpenELEC (3.2.3, I think), the answer is "CHS".
> H. Peter Anvin:
> > OK, it is "CHS"... which most likely means this is a geometry problem.
> 
 
Just to clarify, the two "CHS" messages were seen when booting with 
the initially-failing USB drives (and my guess is that the third USB 
drive that by now has been overwritten was also in "CHS" mode).

_Later_ tests, including the ones with my test.img, are not using CHS 
mode and, more importantly, they are successfully booting the system.


> The current best guess is that your mainboard does not like
> some or all variants of CHS but works with LBA.
> Whether your stick's FAT uses CHS or LBA is decided when you
> partition the stick and format the empty FAT filesystem.
> 
 
There are several reasons for the initial failure to boot; one of the 
possible ones being some potential mix-up and incompatibility with 
some CHS values.

> H. Peter Anvin:
> > find the "magic
> > geometry" that works on that machine, which may be 64/32 for example.
> > However, in CHS mode 1024x64x32 is only 1 GiB,
> 
> So Peter proposes to try 32 sectors per head and 64 heads per
> cylinder when you partiton the USB stick. The partitioning
> program should offer you an opportunity to set these factors.
> 
> Maybe it suffices to format the partitioned stick to a FAT
> filesystem variant which uses LBA.
> 
 
Let's try to avoid special or specific CHS values. Giving the recent 
successful tests, they seem to be not necessary. We are already 
seeing success when using adequate (and commonly-used) Nx255x63 
values in the MBR, in the VBR, formatting as FAT32-LBA with starting 
offset of 2048 sectors. I would suggest keeping this format.

Regards,
Ady.