Date: Wed, 03 Dec 2014 00:48:26 +0800 From: Julian Elischer <julian@freebsd.org> To: Warner Losh <imp@bsdimp.com> Cc: freebsd-current@freebsd.org, FreeBSD Current <current@freebsd.org> Subject: Re: witness and modules. Message-ID: <547DED5A.4050307@freebsd.org> In-Reply-To: <F9C776BA-EAF7-4A38-8AEE-3501C41F40D6@bsdimp.com> References: <54788FF3.3030602@freebsd.org> <2805430.yZtslRjaC7@ralph.baldwin.cx> <547D4947.4040203@freebsd.org> <F9C776BA-EAF7-4A38-8AEE-3501C41F40D6@bsdimp.com>
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On 12/3/14, 12:24 AM, Warner Losh wrote: >> On Dec 1, 2014, at 10:08 PM, Julian Elischer <julian@freebsd.org> wrote: >> >> On 12/1/14, 11:39 PM, John Baldwin wrote: >>> On Friday, November 28, 2014 11:08:35 PM Julian Elischer wrote: >>>> Do we need to compile all modules with witness definitions when >>>> linking with a kernel compiled with witness? >>>> This was true at one stage but I remember some work was done to make >>>> them compatible. >>> You should not need this. modules always call functions in the kernel for >>> lock operations and this functions are what invoke WITNESS. >>> >> that's what I thought but empirical evidence disagrees. >> I'll try some more cases. > I swap back and forth all the time between the two. Kernel modules don’t > change when you compile them with WITNESS or without. > > Warner > it's a 10.0 based system. the zfs kernel module grew a reference to witness_restore and witness_save when it was compiled with witness in opt_global.h. I certainly wouldn't load with a standard kernel. it may have been somethign funny with the zfs compat layer stuff, and I'm pretty sure people don't use zfs as a module much, but it was definitely there. note: it'd probably work the other way around.. a non-witness module would probably load on a witness kernel.. none of the other kernel modules had that extra reference so I think it's specific to zfs. Maybe to the way it was compiled.. the sources are pretty standard but the makefiles are a bit hacked..
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