From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Alex Braunegg <alex.braunegg@gmail.com>, xen-devel@lists.xen.org
Subject: Re: [QUESTION] x86_64 -> i386/i686 CPU translation between xl and qemu binary?
Date: Thu, 4 Feb 2016 22:22:27 +0000 [thread overview]
Message-ID: <56B3CF23.4000404@citrix.com> (raw)
In-Reply-To: <56b3cb85.c542620a.6af1e.ffff9622@mx.google.com>
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.
~Andrew
next prev parent reply other threads:[~2016-02-04 22:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-04 22:06 [QUESTION] x86_64 -> i386/i686 CPU translation between xl and qemu binary? Alex Braunegg
2016-02-04 22:22 ` Andrew Cooper [this message]
2016-02-04 23:14 ` Steven Haigh
2016-02-05 0:12 ` Andrew Cooper
2016-02-05 9:56 ` Ian Campbell
2016-02-04 23:44 ` Alex Braunegg
2016-02-05 0:04 ` Andrew Cooper
2016-02-05 0:18 ` Alex Braunegg
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