From owner-freebsd-current@FreeBSD.ORG  Wed Apr 21 15:26:06 2010
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Date: Wed, 21 Apr 2010 17:23:38 +0200
From: Roman Divacky <rdivacky@FreeBSD.org>
To: Alexander Best <alexbestms@wwu.de>
Message-ID: <20100421152338.GA77210@freebsd.org>
References: <permail-201004211520571e86ffa800002675-a_best01@message-id.uni-muenster.de>
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Cc: freebsd-current@FreeBSD.org
Subject: Re: [CFT]: ClangBSD is selfhosting, we need testers now
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On Wed, Apr 21, 2010 at 05:20:57PM +0200, Alexander Best wrote:
> i might have stumbled upon a problem with clang. i've compiled a kernel from
> the clang branch using `make kernel INSTKERNNAME=clang` and booted from it.
> i'm now experiencing audio problems with mp3s and certain video files.
> playback is awfully slow and the audio output gets distorted massively. `top`
> however reports no high cpu load and `vmstat -i` doesn't report anything
> unusual either.
> 
> this problem doesn't occur with a regular gcc-kernel.
> 
> both kernels are running under a regular (gcc) world.
> 
> i thought it might be a problem with acpi, but disabling acpi
> (hint.acpi.0.disabled=1) gives me a system freeze.

I've heard about this problem but did not manage to reproduce that.

can you try to bisect what file is being miscompiled? ie. compile
half of the kernel with gcc and half with clang and bisect this
way to a single file.

we can work from there...