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From: | Jason Wessel |
Subject: | Re: [Qemu-devel] [PATCH 0/3] PPC: E500: Support SPE guest |
Date: | Tue, 23 Aug 2011 12:00:00 -0500 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110617 Thunderbird/3.1.11 |
On 08/22/2011 11:55 PM, Alexander Graf wrote: > When I bumped into Jason on Linuxcon, we tried out to run the e500 target > on his Windriver build that used SPE and immediately ran into emulation > issues. Fortunately there weren't too many, so here are the patches to get > a guest using SPE instructions working just fine. > The patch set looks good to me. I tried it out this morning. I have a patch that implements enough of the the dbcr0, dbsr, and msr DE bit in order to single step, but I am seeing random fatal mmu faults. Before we go down the route of implementing more pieces, I am interested to know if you see the same behavior, or if you had any ideas around how to further debug it. Using just your patch series + the QEMU HEAD + the SPE enabled rootfs + qemu NFS mounting the rootfs, here is the "litmus test" to see if you experience the fatal mmu faults to user space. ulimit -c unlimited while [ 1 ] ; do echo 3 > /proc/sys/vm/drop_caches (echo quit ; sleep 2) | gdb /bin/ls || break done I find that this runs between 1-15 times and crashes with a core file. Looking at the core file it is usually in a malloc or free operation in the user space, and always in the page fault handler in the kernel. This really amounts to running a medium sized app through the startup, which does a whole bunch of malloc and free because it maps in the elf debug info for /bin/ls , and gdb is not really getting used for anything to ptrace. Jason. |
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