Re: [Qemu-devel] error kvm: virtio: trying to map MMIO memory
Thank you for your help, I have been able to see where was the bug ! Indeed, I was losing some address values along the way in a callback function whereas I thought they were kept memorized. Regards Stéphanie
Re: [Qemu-devel] error kvm: virtio: trying to map MMIO memory
2011/7/17 Stéphanie Ouillon steph.ouil...@gmail.com: I have been facing a problem for 3-4 days with my virtio network device driver in qemu: when I load the driver, I get the following error: kvm: virtio: trying to map MMIO memory [...] Would anybody have a clue about what kind of bug would provoke this error in qemu ? It means a descriptor has an addr field that is not a bus address backed by RAM. Instead the incorrect address is to a MMIO memory region. Normally all buffers that you pass via virtio are guest physical RAM addresses, hardware mapped registers (MMIO) should not be passed over virtio and there's usually really no reason to do that. This suggests you are setting an incorrect address in the guest driver or are forgetting to set the address field thereby causing a stale value to be read by QEMU. I suggest adding the following to qemu/hw/virtio.c:virtqueue_map_sg() right before the if statement that checks for failed memory map: fprintf(stderr, addr TARGET_FMT_plx len TARGET_FMT_plx is_write %d\n, addr[i], len, is_write); Compare the addresses that QEMU is seeing with those you have given to virtio in the guest kernel. It should be possible to correlate the buffers that the guest wants to give the host with what QEMU sees. Let us know if you need any more help debugging. Stefan
[Qemu-devel] error kvm: virtio: trying to map MMIO memory
Hello, I am porting virtio device drivers for DragonFly BSD for a GSoC project. [1] I have been facing a problem for 3-4 days with my virtio network device driver in qemu: when I load the driver, I get the following error: kvm: virtio: trying to map MMIO memory And then the machine crashes immediately (I started the vm in a screen to see this message). It seems to be linked with the call of a bus_space_write_2 function [2] inside a virtio_enqueue_commit function in virtio.c [3]. But without more information about this type of error message (I found some patches or bug reports on the net, but I am not sure they match in my case), I found it difficult to locate it. Would anybody have a clue about what kind of bug would provoke this error in qemu ? Thank you ! Stéphanie Ouillon [1] http://github.com/arroway/virtio_DragonFlyBSD/tree/dev-net/net [2] source code in DragonFly BSD http://fxr.watson.org/fxr/source/cpu/i386/include/bus_at386.h?v=DFBSD;im=bigexcerpts#L887 [3] at l.465: http://github.com/arroway/virtio_DragonFlyBSD/blob/dev-net/virtio.c
