Date: Thu, 01 Aug 2013 07:28:33 -0600 From: Ian Lepore <ian@FreeBSD.org> To: Mattia Rossi <mattia.rossi.mate@gmail.com> Cc: freebsd-arm@FreeBSD.org Subject: Re: Kernel Panic on DREAMPLUG: Alignment Fault 1 Message-ID: <1375363713.45247.193.camel@revolution.hippie.lan> In-Reply-To: <51FA1D2B.9090009@gmail.com> References: <51F92F79.9010809@gmail.com> <1375309907.45247.185.camel@revolution.hippie.lan> <51F9C81A.7000106@gmail.com> <1375358623.45247.189.camel@revolution.hippie.lan> <51FA1D2B.9090009@gmail.com>
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On Thu, 2013-08-01 at 10:32 +0200, Mattia Rossi wrote: > On 01/08/13 14:03, Ian Lepore wrote: > > On Thu, 2013-08-01 at 04:29 +0200, Mattia Rossi wrote: > >> On 01/08/13 00:31, Ian Lepore wrote: > >>> On Wed, 2013-07-31 at 17:38 +0200, Mattia Rossi wrote: > >>>> Hi all, > >>>> > >>>> this might be related to the WLI-UC-GNM Alignment Fault, but definitely > >>>> has nothing to do with Wireless LAN. > >>>> It rather seems that there's a problem with the USB subsystem. > >>>> > >>>> See dmesg an backtrace below. > >>>> [snip] > >>>> > >>>> Currently trying to find where the issue could be. > >>>> > >>>> Mat > >>> This is a strange abort, and if it's usb-related that's only accidental > >>> I think. It says it's an alignment fault, but the fault address reg has > >>> a 32-bit aligned value in it. That makes me think it must be an > >>> ldrd/strd instruction (requires 64-bit alignment) that's faulting. > >>> > >>> Is this compiled with clang? I think it emits such instructions and gcc > >>> doesn't. Except I don't think clang should use those instructions on > >>> armv5, because of the alignment requirements. > >>> > >>> -- Ian > >> Hi Ian, > >> > >> sorry, forgot to add that contrary to the WLI-UC-GNM problem, I'm still > >> compiling using gcc on FreeBSD 9.1 > >> > >> The abort is completely reproducible each time at the same place... > >> I've tried to recompile the kernel a few times, also changing the root > >> device, but it gets stuck there and aborts.. > >> > >> I actually have no clue on what's going on here. Any hints on how to get > >> more information about this? > >> > >> Cheers, > >> > >> Mat > > Actually, it looks like you're using clang (I keep forgetting this comes > > out in dmesg now): > > > >>> FreeBSD 10.0-CURRENT #9 r253846M: Wed Jul 31 17:24:31 CEST 2013 > >>> root@freebsd9.1-base:/usr/obj/arm.arm/usr/devel/dreamplug/sys/DREAMPLUG-100m > >>> FreeBSD clang version 3.3 (tags/RELEASE_33/final 183502) 20130610 > > Is the 'M' in r253846M anything significant? > > > > I haven't built for dreamplug in a long time (I haven't done much of > > anything with computers for several months). I'll get a build going and > > see if I get the same kind of problems. > > > > -- Ian > > > Gee... I guess I'm using CLANG then... > So, this messes a bit with my understanding of the relation of host and > guest... > I always thought, that the host system decides which compiler gets used > for cross-compiling, and not the guest (which means the source tree) > So If my default compiler is gcc on the host, everything should be > compiled with gcc. > Given that I haven't changed anything of that, how comes that the kernel > is compiled using clang? > Especially given that the clang version on the host will not be a very > up-to-date version? > Or does clang get built during the make process, and then used as the > compiler? > > Anyhow, I'll try to compile with gcc, and see what happens. The host system's compiler (gcc in your case) is used to build the selected compiler from src/, then that new compiler is used to build the rest of src/ into a runnable system. You can define WITHOUT_CLANG_IS_CC and WITHOUT_EABI to use gcc, and you should probably add WITHOUT_CLANG to avoid building it since it won't be used (and it takes forever to build). After rebuilding with clang/eabi I get exactly the same crash in the same spot (even the same fault address). I'll see if I can figure out what the actual problem is. -- Ian
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