Date: Thu, 1 May 2008 17:29:35 +0200 From: Juergen Lock <nox@jelal.kn-bremen.de> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-amd64@freebsd.org Subject: Re: kernel/kld debugging on amd64 (qemu gdbstub, gdbinit, asf(1)...) Message-ID: <20080501152935.GA2940@saturn.kn-bremen.de> In-Reply-To: <200805011014.34348.jhb@freebsd.org> References: <20080501105138.GA30798@saturn.kn-bremen.de> <200805011014.34348.jhb@freebsd.org>
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On Thu, May 01, 2008 at 10:14:34AM -0400, John Baldwin wrote: > On Thursday 01 May 2008 06:51:38 am Juergen Lock wrote: > > Before I forget, here are some things I found out while debugging the > > kqemu amd64 SMP issue... > > > > 1. I used a patched kgdb to be able to use it with qemu's gdbstub > > (kgdb -r 127.1:1234 kernel.debug), that patch I already posted: > > http://docs.freebsd.org/cgi/mid.cgi?20080304213153.GB15959 > > (Yeah you can also used regular gdb or gdb66 from ports with qemu's > > gdbstub, but those don't understand kernel stack frames and maybe > > other things...) > > This patch just went into the tree (a variant of it) in the commits to kgdb in > HEAD earlier this week. > Ah cool! > > 2. the ps and kldstat macros from src/tools/debugscripts/gdbinit.kernel > > (and probably others) use %08x for pointers, so on 64 bit archs like amd64 > > the upper half gets chopped off. I didn't fix this correctly tho, but > > instead defined my own ps64 and kldstat64 macros using %016lx... > > Try using macros at www.freebsd.org/~jhb/gdb/gdb6 instead as they handle > 64-bit vs 32-bit. > Ah, good to know for next time... > > 3. asf(1) also didn't work correctly for amd64 (bss and data were wrong), > > here is the patch I ended up using: (maybe you want to ifdef for amd64 > > instead of checking for zero VMA tho) > > I haven't seen this, but I also haven't used asf(8) on amd64. You can grab > the kgdb sources from HEAD though and then you can use kgdb's native kld > support (i.e. add-kld and the shared library stuff) for remote targets to > load symbols. > OK, will try next time. :) Thanx, Juergen
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