Date: Sat, 04 Sep 2010 22:54:07 +0300 From: Andriy Gapon <avg@freebsd.org> To: freebsd-current@freebsd.org Subject: Re: problem with amd64 minidump Message-ID: <4C82A3DF.2000809@freebsd.org> In-Reply-To: <4C7FA1BF.30206@freebsd.org> References: <4C7F782B.8050507@freebsd.org> <4C7FA1BF.30206@freebsd.org>
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on 02/09/2010 16:08 Andriy Gapon said the following: > on 02/09/2010 13:10 Andriy Gapon said the following: >> >> Not sure if this is some local issue or a problem in FreeBSD code. >> I remember minidumps working perfectly well for me, but now I can not get data >> from them. >> Example: >> dmesg -M /var/crash/vmcore.4 >> dmesg: _kvm_vatop: direct map address 0xffffff012fffffe0 not in minidump >> dmesg: kvm_read: invalid address (0xffffff012fffffe0) > > Not sure if it can help, but it seems that this virtual address in DMAP > corresponds to a physical address in the last page of RAM. > Do we use that for anything special? Message buffer? > I had a quick look at getmemsize() function in sys/amd64/amd64/machdep.c and it > looks like the following code in the function could be doing just that: > > Maxmem = atop(phys_avail[pa_indx]); > > /* Trim off space for the message buffer. */ > phys_avail[pa_indx] -= round_page(MSGBUF_SIZE); > > /* Map the message buffer. */ > msgbufp = (struct msgbuf *)PHYS_TO_DMAP(phys_avail[pa_indx]); > > Oh, and yeah: > (gdb) p msgbufp > $4 = (struct msgbuf *) 0xffffff012fffffe0 > > But we do dump the message buffer. > But somehow its dmap address is not resolved correctly. > > This should ring a bell for someone knowledgeable of minidump and libkvm code, I > believe. Just for the record: this was triggered by having non-default MSGBUF_SIZE, see r212174 for the fix. -- Andriy Gapon
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