[syslinux] Chaining with chain.c32 from syslinux 6.01 error

Adrian Irimia adixtx at yahoo.com
Fri Jul 26 04:51:46 PDT 2013

Ok , I will make some checks.
However, adding 'relax' option did not work in 6.01 version.

P.S. My usb flash disk is formated with HP flash format tool with default options , no customizations (wich makes 4 partitions). Then I run syslinux.exe to install syslinux on mbr. All on the same physsical machine.

 From: Michal Soltys <soltys at ziu.info>
To: Adrian Irimia <adixtx at yahoo.com>; For discussion of Syslinux and tftp-hpa <syslinux at zytor.com> 
Cc: Matt Fleming <matt at console-pimps.org> 
Sent: Friday, July 26, 2013 12:24 PM
Subject: Re: [syslinux] Chaining with chain.c32 from syslinux 6.01 error

On 2013-07-24 15:39, Adrian Irimia wrote:
> I just tested 6.02-pre10 version.
> On physsical machine it is booting ok now, but chain.c32 result is the same errors :  ERR: Primary partition (in MBR) with invalid offset and/or length.
>    ERR: Cant't find myself on the drive I booted from
> Adding 'relax' option to chain.c32 invocation resolves the problem.

Then this is almost for sure related to the size (as seen and reported 
by bios) of usb stick. The only checks done (that lead to the 1st error, 
with 2nd error being consequence of the first) on primary partition are:

size != 0
start != 0
start + size don't wrap around
start + size don't go beyond disk size

The last check above is the one failing. The reason behind adding 
'relax' was in essence 'be quiet, nothing is wrong and bios is stupid'.

If you want to avoid relying on 'relax', make sure the main partition 
spawning whole disk is a tiny bit shorter than the whole disk.

If you have some tool like say hdt.c32 on the stick installed as well, 
you could verify what sizes are reported under qemu and under physical 
machine (to be sure that this is really the case).

> In qemu the boot and chaining works ok (without 'relax' option).
> ________________________________
>   From: Matt Fleming <matt at console-pimps.org>
> To: Adrian Irimia <adixtx at yahoo.com>
> Cc: "syslinux at zytor.com" <syslinux at zytor.com>
> Sent: Wednesday, July 24, 2013 9:57 AM
> Subject: Re: [syslinux] Chaining with chain.c32 from syslinux 6.01 error
> On Tue, 23 Jul, at 08:06:46AM, Adrian Irimia wrote:
>> Yes. Prior versions (all to 6.01 inclusive) are working very well.
>>  And yes it fail before invoking chain.c32 (as I said in qemu there is no errors).
> Could you try 6.02-pre10?

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