Re: [Gptfdisk-general] Bug#637572: gdisk: fails to write protective MBR

[Rod S. <rod...@ro...>]

On 08/24/2011 02:08 PM, Arno Schuring wrote:
> (replying to myself because I seem to have lost your message, apologies
> Rob)
>
> Arno Schuring (ael...@ho... on 2011-08-16 00:55 +0200):
>> Hi,
>>
>>
>> I've taken a (cursory) look at the diffs, version 0.7's MBR is always
>> all-zeroes. I did get to try these disks on i386 as well, and there it
>> works fine, so it's not disk-related. I guess it's either an
>> architecture-specific bug or a compiler gotcha.
>
> I've been unable to reproduce this. The local compile on the arm box
> produces a correctly functioning executable, so I've not yet been
> playing with compile-time options and such.
>
> My (very basic) approach has been:
> # apt-get build-dep gdisk/testing
> $ apt-get source gdisk/testing
> $ cd gdisk-0.7.2
> $ dh_auto_build
> # ./gdisk /dev/sda
>
> This is with gcc version 4.4.5 (Debian 4.4.5-8) on an up-to-date
> Squeeze install. Gdisk is from testing, and from the QA logs I can see
> that the package is built with gcc 4.6.
>
> Upgrading to 4.6 on this box is not possible (it requires me to upgrade
> libc6), I'll pursue this once I have a working cross-compiler or
> chroot. Pointers welcome :)

This certainly sounds like an issue that's specific to GCC 4.6. (I'm not 
implying that GCC 4.6 is buggy, necessarily; it's more likely that it's 
just doing something subtly different from other versions of GCC and my 
code is assuming a different behavior.) I don't currently have GCC 4.6 
installed on any of my computers, but I'll get it up and running on one 
of them. With any luck that'll enable me to reproduce and fix the bug.

In the meantime, the workaround for you is obvious: Use your 
locally-compiled (with GCC 4.4.5) version of gdisk!

-- 
Rod Smith
rod...@ro...
http://www.rodsbooks.com