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Message #19634
[Bug 1235277] Re: armhf: virtio_mmio support
** Tags added: patch
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https://bugs.launchpad.net/bugs/1235277
Title:
armhf: virtio_mmio support
Status in “linux” package in Ubuntu:
In Progress
Status in “linux” source package in Saucy:
In Progress
Bug description:
SRU Justification:
Impact: qemu 1.6 adds support for virtio memory mapped devices (like
net and block) on arm. While S will probably ship with qemu 1.5, we
know it'll be provided in a ppa and we want to take advantage of the
speedup offered by virtio, so
1) turn on virtio_mmio on armhf (generic and generic-lpae)
2) uniform VIRTIO* support among all the different archs, making it a compiled-in options like on i386 and amd64
Fix: apply the attached config patch and recompile a kernel with it
Testcase: try booting a qemu kvm using a kernel without this patch:
sudo qemu-system-arm -machine vexpress-a15 -cpu cortex-a15 -enable-kvm
-m 512M -kernel /boot/vmlinuz-`uname -r` -append "console=ttyAMA0
earlyprintk=serial root=/dev/mmcblk0 ro rootfstype=ext4" -serial stdio
-dtb /lib/firmware/`uname -r`/device-tree/vexpress-v2p-ca15-tc1.dtb
-initrd /boot/initrd.img-`uname -r` -drive if=sd,cache=writeback,file
=saucy-server-cloudimg-armhf.img -net nic -net
user,hostfwd=tcp::2223-:22 -display none
and then try to boot another instance using a kernel with the config
patch applied:
sudo qemu-system-arm -machine vexpress-a15 -cpu cortex-a15 -enable-kvm
-m 512M -kernel /boot/vmlinuz-`uname -r` -append "console=ttyAMA0
earlyprintk=serial root=/dev/vda ro rootfstype=ext4" -serial stdio
-dtb /lib/firmware/`uname -r`/device-tree/vexpress-v2p-ca15-tc1.dtb
-initrd /boot/initrd.img-`uname -r` -drive
if=none,cache=writeback,file=saucy-server-cloudimg-armhf.img,id=foo
-device virtio-blk-device,drive=foo -display none -netdev tap,id=tap0
-device virtio-net-device,netdev=tap0
the difference is noticeable to the naked eye.
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References