[syslinux] boot fails on some system

Jethro Tull heavytull at hotmail.com
Fri Apr 14 11:25:10 PDT 2017


On Fri, 14 Apr, 2017, 11:13:43 +0000, Jethro Tull via Syslinux wrote:
> On Fri, 14 Apr, 2017,  0:05:05 +0000, Ady Ady via Syslinux wrote:
> [ ... ]
> > The suggested command to write to the MBR area is to first _unmount_ 
> > all the devices related to the physical device you want to write to, 
> > and then execute the 'dd' command as described at:
> > 
> >  http://www.syslinux.org/wiki/index.php/Mbr#Write 
> > 
> > Beware: use the correct "sdx" device for your case / OS; writing to 
> > 'sda" if the device you are aiming at is a different one will cause you 
> > much more problems.
> > 
> > I would also add the 'sync' command, after dd'ing the mbr.bin file to 
> > the desired output device and/or after finishing any write operation to 
> > a portable device you are about to disconnect.
> > 
[ ... ]
> > 
> > I would suggest repeating the procedure with the FAT fs, this time 
> > using dd to write the MBR.
> > 
[ ... ]
> > Ady.
> 
[ ... ]
> As for the device file, if you read back my email you'll notice that I indeed
> took that care about the difference in naming of devices and partitions in
> linux.
[ ... ]
> I will repeat the procedure with using dd for writing the mbr and sync
> afterwards.

Here it is, I tried following your procedure, i.e. using :

$dd if=mbr.bin of=/dev/sdx bs=440 count=1 conv=notrunc
$sync

where "sdx" is my device. I repeat I indeed used the device file and not any
partition file. I took care of using the right device. Mind that hadn't I do
so previously, I would have ended up in failing to boot with both computers.

This time I only tested with FAT partitions, so I used syslinux command, and
I tried both primary and logical partitions. I didn't tell it previously but
in my previous tests I had also tried with both primary and logical
partitions. The results were the same. I'm trying to make a multi-boot usb
hard drive, i.e. hosting several boot programs to be booted upon user choice.
Using logical partitions gives more flexibility as for the number ofboot
images that I can install on the drive. But I've only tested with one so far.

Back to my new tests with use of "dd" and "sync" to copy syslinux bin.mbr to
the device's mbr. I got a slighly different result but still it failed on the
same computer. The other one booting properly as expected and as previously.
This time the failing computer does not reboot, I get the message :

"Missing operating system." 
"Operating System not found" 

and keep still ...  I can reboot the computer with Ctrl + Alt + Del.


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