kernel-packages team mailing list archive

[Paolo Pisati <1235277@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

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.

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Incomplete

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https://bugs.launchpad.net/bugs/1235277

Title:
  armhf: virtio_mmio support

Status in “linux” package in Ubuntu:
  Incomplete

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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