Same situation here: Firefox can't handle ~/.mozilla to be a virtio-9p mount. Here the subvolume is ext4, mounted only at /home.
I also noticed that chromium is working, but it complains about some errors: getrlimit(RLIMIT_NOFILE) failed [4809:4839:0804/230514:ERROR:backend_impl.cc(1365)] Unable to map Index file [4809:4839:0804/230514:ERROR:backend_impl.cc(1365)] Unable to map Index file [4809:4840:0804/230514:ERROR:cache_creator.cc(133)] Unable to create cache [4845:4845:0804/230514:ERROR:sandbox_linux.cc(340)] InitializeSandbox() called with multiple threads in process gpu-process -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1459622 Title: firefox hang with virtfs Status in QEMU: New Bug description: Firefox hangs once it starts to load pages. I tried to delete .cache/mozilla/ and .mozilla/ but it doesn't help. But if I mount tmpfs on to .mozilla (not necessary for .cache/mozilla/), pages loads fine. I started the vm as root (sudo) with the following command: qemu- system-x86_64 -enable-kvm -m 4G -virtfs local,mount_tag=qemu,security_model=passthrough,path=/mnt/qemu/ -kernel /mnt/qemu/boot/vmlinuz-linux -initrd /mnt/qemu/boot/initramfs- linux-fallback.img -append 'rw root=qemu fstype=9p' -usbdevice tablet -vga qxl -spice port=12345,disable-ticketing /mnt/qemu is a btrfs snapshot of the subvolume used as the host root Arch Linux, qemu 2.3.0, firefox 38.0.1 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1459622/+subscriptions