On 2016-02-05 09:22, Andrew Cooper wrote:
On 04/02/2016 22:06, Alex Braunegg wrote:
root 30511 46.4 0.1 398728 1860 ? RLsl 08:47 0:27
/usr/lib/xen/bin/qemu-system-i386 -xen-domid 6 -chardev
socket,id=libxl-cmd,path=/var/run/xen/qmp-libxl-6,server,n
owait -no-shutdown -mon chardev=libxl-cmd,mode=control -chardev
socket,id=libxenstat-cmd,path=/var/run/xen/qmp-libxenstat-6,server,nowait
-mon chardev=libxenstat-cmd,mode=control
-nodefaults -name test2 -vnc
0.0.0.0:0,websocket,x509=/etc/pki/xen,password,to=99 -display none
-serial
pty -device VGA,vgamem_mb=16 -boot order=cd -usb -usbdevice tablet
-soundhw
ac97 -device rtl8139,id=nic0,netdev=net0,mac=00:16:3e:f1:48:8c
-netdev
type=tap,id=net0,ifname=vif6.0-emu,script=no,downscript=no -machine
xenfv -m
496 -drive file=/dev/zvol/stor
age0/xen/test2/disk_sda,if=ide,index=0,media=disk,format=raw,cache=writeback
-drive
file=/storage0/data-shares/iso/CentOS-6.5-x86_64-minimal.iso,if=ide,index=2,
readonly=on,media=c
drom,format=raw,cache=writeback,id=ide-5632
------------------------------------------
So - to me it appears that xl is performing some sort of x86_64 ->
i386/i686
instruction translation to make things work.
Would this not be introducing a performance impediment by having some
sort
of extra translation processing going on between xl and the qemu
binary?
Qemu is only used for device emulation when used with Xen, not CPU
emulation.
The "-machine xenfv" tells this to Qemu, and "-xen-domid 6" tells it
which Xen domain to connect to.
All HVM domains run with hardware virtualisation extensions, which are
managed by Xen itself.
Hi Andrew,
Thanks for this response - to ensure I have this correct, there is no
need for qemu-upstream to build qemu-system-x86_64 as the CPU is
directly handled by Xen and not by qemu - thereby passing through the
capabilities of the CPU directly to the guest. As such, as long as qemu
starts on a 64 bit machine it will be able to run 64 bit OS/kernel etc.
I ask this as I see a number of qemu packages that do include
qemu-system-x86_64 as well as qemu-system-i386 - which makes me seek
clarification. I would assume that these are just not built to use Xen
as the hypervisor for hardware acceleration?
--
Steven Haigh
Email: net...@crc.id.au
Web: https://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897
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