[syslinux] Linux syslinux-3.72 does not update boot block for SD devices

[H. Peter Anvin]

Ferenc Wagner wrote:
> "H. Peter Anvin" <hpa at zytor.com> writes:
> 
>> dd if=/usr/lib/syslinux/mbr.bin of=/dev/sdb bs=440 count=1
>>
>> The reason this isn't automatic is that this is sometimes not
>> possible under Linux.
> 
> That makes me wonder.  When is it not possible?
> 

Linux is a little too flexible some times; when dealing with things like 
loopback devices you can't necessarily find the master device.  Worse, 
with older Linux kernels there are some conditions in which you could 
end up poking the wrong device.

> Also, most docs recommend cat mbr.bin >/dev/sdb.  Is there any
> difference?

I prefer the dd= statement since it will prevent overwriting more than 
the 440 bytes of the MBR proper in case the file is corrupt.  Just a safety.

	-hpa