Date: Wed, 28 Apr 2004 10:16:00 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Ruslan Ermilov <ru@FreeBSD.org> Cc: alpha@FreeBSD.org Subject: Re: pmap_emulate_reference() panics still ongoing Message-ID: <16527.48288.319462.214843@grasshopper.cs.duke.edu> In-Reply-To: <20040428135850.GA43106@ip.net.ua> References: <20040428084120.GA25958@ip.net.ua> <16527.42479.941859.703698@grasshopper.cs.duke.edu> <20040428135850.GA43106@ip.net.ua>
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Ruslan Ermilov writes: > On Wed, Apr 28, 2004 at 08:39:11AM -0400, Andrew Gallatin wrote: > > > > Ruslan Ermilov writes: > > > Andrew, > > > > > > This is with latest src/sys/alpha/alpha/pmap.c,v 1.146. > > > > > > db> where > > > Debugger() at Debugger+0x38 > > > __panic() at __panic+0x228 > > > pmap_emulate_reference() at pmap_emulate_reference+0x15c > > > trap() at trap+0x3dc > > > XentMM() at XentMM+0x2c > > > --- memory management fault (from ipl 0) --- > > > --- user mode --- > > > > Damn. Did the change make it any worse for you? > > > No, I can't say this made things any worse. ;) Good. > This is not a very fast runner (166MHz EV4, 64MB RAM, swap > is used). Since I've upgraded it to 5-CURRENT, running the > GENERIC kernel, my 5 attempts to build world ended up with > this panic (often the panic message was unreadable, this one, > after I've upgraded kernel to the latest pmap.c, was probably > a good exception). Now I've built the debug version of the > kernel. Will it be of some help? Wow, and I thought my 600MHz ev67 was slow. At least you can reproduce this -- I can't. Given that I always run a bwx-enabled kernel, and I never see it, I wonder if there might be some corruption caused by 8 or 16 bit data fields in the vm or pmap systems which share a 32-bit word, but which are separately locked. I'm thinking that the read-modify-write which a non bwx kernel needs to do could lead to data-corruption in this case. I don't see anything immediately, but then I don't know the vm system very well. > (Hardly relevant, but it was happy running 4.10-RC.) Very relevant -- it means the bug is new to 5.x Drew
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