RE: [Xen-users] Xen, Dual Core, Windows and QNX

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

Windows should work as expected.

 

QNX is probably (from a historical standpoint) using segmented with limits and a base that is non-zero, something that doesn't work well with Xen... There are several of places within Xen where segments are mismanaged (assumed to have base=0 and limit that is "big enough" [and the latter isn't much of a problem unless the code is incorrect in the first place or using some "funny tricks" - but having a weird overwriting of some memory area instead of a blue-screen/kernel panic type situation is of course not a nice thing to have happen!]).  

 

You do always need Dom0.

 

Also, real-time-ness of something running on top of Xen with full virtualization will NOT be anywhere near "realtime", unless you play lots of tricks with the scheduling settings on the system. And even then, there will still be a bunch of overhead in Xen that determines the worst-case real-time-ness. It's probably fine if you don't have any HIGH real-time requirements [i.e. your real-time-ness is in the milliseconds rather than microseconds range].

 

Please DO TRY to install QNX, and let us know how it works out - it is entirely possible that I'm wrong in my understanding of QNX and it's usage of segment registers [it's been more than 5 or more years since I last had any connection with QNX].

 

--

Mats

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From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Bryan Prosser
Sent: 31 August 2006 15:15
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Xen, Dual Core, Windows and QNX

I'm fairly new to both Xen and Linux, my boss wants me to try and get Xen working on a new dual core running both Windows and QNX (we need to do some real time processing). Ideally he wants Windows to be a host (although from what I have read this isn't possible yet?) and QNX as a guest. I'm guessing a Linux Dom0 will be needed and then the others run as guests. Does anyone know of any issues involved with installing QNX on Xen and getting real-time performance from it, so far ive only run Xen on FC5 with an FC5 guest and have read the instructions on the Zen Wiki about windows installations but don’t know how supported QNX will be.

Any help or advice would be greatly appreciated!

Bryan

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