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Re: [Xen-devel] Testing nested virtualization on Intel CPUs
| To: | Tim Deegan <tim@xxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] Testing nested virtualization on Intel CPUs |
| From: | Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> |
| Date: | Wed, 21 Sep 2011 17:50:39 +0100 |
| Cc: | Eddie Dong <eddie.dong@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx |
| Delivery-date: | Wed, 21 Sep 2011 09:53:30 -0700 |
| Envelope-to: | www-data@xxxxxxxxxxxxxxxxxxx |
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| Sender: | xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
On Wed, 21 Sep 2011 17:38:10 +0100 Tim Deegan <tim@xxxxxxx> wrote: > At 22:18 -0700 on 20 Sep (1316557136), AP wrote: > > > Yes, booting Xen as a nested guest is very slow at startup, because of > > > how Xen relocates the bottom 1MB at boot time. You might find that > > > 32-bit Xen boots faster. > > > > Could please expand a little on why the relocation causes it to slow down? > > IIRC, the relocation itself is very slow because Xen just copies the low > 1MB, which includes the VGA hole, so there are a lot of emulated reads. That seems a bit odd - ISA space reads can have side effects. Alan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel |
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