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Subject: Re: Phantom nulls in usbdevs.h during 9-STABLE kernel build
From: Dimitry Andric <dim@FreeBSD.org>
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Date: Thu, 4 Jul 2013 15:08:57 +0200
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To: J David <j.david.lists@gmail.com>
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On Jul 4, 2013, at 04:43, J David <j.david.lists@gmail.com> wrote:
> We are seeing strange problems building the kernel on 9-STABLE.  The
> problem is intermittent and will go away if we build enough times in a row
> without making any changes.
> 
> 
> The problem seems to be that the usbdevs.h file (which appears to be
> automatically generated) gets random NULL bytes in it.
...
> On the second failure posted below I took a hex dump of the usbdevs.h file.
> I don't see any NULLs at the target location, which is an empty line.
> (Just 0a 0a for the empty line.)  In fact there are no nulls anywhere in
> the file.

So the actual file does *not* have any NUL characters in it?  What
happens if you run e.g. sha1(1) over it a million times?

If there are NUL characters, there might be a bug in the awk script that
generates usbdevs.h.  If there are no NUL characters, and you get a
random failure each time, there might be a bug in clang.  But did you
mean you also saw it with gcc?

-Dimitry