Red Hat Bugzilla – Bug 489274
[RHEL5.3 Xen]: Cannot attach > 16 PV disks using PV-on-HVM drivers
Last modified: 2009-09-02 04:55:11 EDT
Description of problem:
While attempting to do some testing on a RHEL-5.3 guest, I wanted to attach 32 disks to an i386 guest. I used the following command 30 times:
xm block-attach rhel5fv_i386 tap:aio:/var/lib/xen/images/disk.img /dev/xvd? w
Devices xvda->xvdq attached just fine, and I was able to use them in the guest. However, devices beyond that (/dev/xvdr and higher) did not show up in the guest. I also performed this test on a PV i386 guest, a PV x86_64 guest, and an FV x86_64 guest; in all 3 of those cases, it worked just fine. So this seems to be particular to 32-bit FV on 64-bit dom0.
This recent upstream discussion may also be relevant here:
Created attachment 337016 [details]
Backport of xen-unstable c/s 18266 and 19266 that seems to fix the problem
You can download this test kernel from http://people.redhat.com/dzickus/el5
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