Bug 224587 - Make sure PV-on-HVM xen has an entropy source
Summary: Make sure PV-on-HVM xen has an entropy source
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: xen
Version: 5.1
Hardware: All
OS: Linux
Target Milestone: ---
: ---
Assignee: Xen Maintainance List
QA Contact: Virtualization Bugs
Depends On:
Blocks: 246139 222399 246258 296411
TreeView+ depends on / blocked
Reported: 2007-01-26 15:37 UTC by Bryn M. Reeves
Modified: 2018-10-19 21:14 UTC (History)
2 users (show)

Clone Of:
Last Closed: 2007-09-03 09:01:26 UTC

Attachments (Terms of Use)
make platform_pci interrupts use SA_SAMPLE_RANDOM (594 bytes, patch)
2007-01-26 16:27 UTC, Bryn M. Reeves
no flags Details | Diff

Description Bryn M. Reeves 2007-01-26 15:37:47 UTC
Description of problem:
When using PV-on-HVM drivers with Xen, there is no interrupt source to provide
data to the entropy pool used by /dev/random and /dev/urandom. This leads to
PV-on-HVM guests blocking on attempts to read /dev/random (urandom will fall
back to a pseudo-RNG and not block). 

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Create a HVM guest configured to use vbd for the system disk
2. Read from /dev/random, for e.g.:
hexdump /dev/random

Actual results:
The reading process will block for ever waiting for the entropy pool to be refilled.

Expected results:
The reading process makes progress as interrupts replenish the data in the
entropy pool.

Additional info:
PV-on-HVM is not supported in RHEL5 GA and no PV-on-HVM drivers are shipped.
This bug targets future releases which may contain this support.

Comment 1 Bryn M. Reeves 2007-01-26 16:27:56 UTC
Created attachment 146686 [details]
make platform_pci interrupts use SA_SAMPLE_RANDOM

This patch was created by Fujitsu's engineers and submitted to upstream xen:


The patch was merged in xen-unstable in the following commit:


Comment 3 RHEL Product and Program Management 2007-03-21 22:28:30 UTC
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update

Comment 4 Brian Stein 2007-06-28 20:00:12 UTC
Review & test in 5.1 beta.

Comment 5 Red Hat Bugzilla 2007-07-25 00:32:46 UTC
change QA contact

Comment 8 Gerd Hoffmann 2007-09-03 09:01:26 UTC
xen-3.1 upstream (which the upcoming pv-on-hvm packages are based on) has the
fix merged.

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