Bug 220305 - Release notes requried for 16GB kernel-xen limit on x86
Release notes requried for 16GB kernel-xen limit on x86
Status: CLOSED CURRENTRELEASE
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel-xen (Show other bugs)
5.0
All Linux
medium Severity medium
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Assigned To: Don Domingo
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Depends On:
Blocks: 197865
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Reported: 2006-12-20 05:33 EST by Stephen Tweedie
Modified: 2010-03-14 17:31 EDT (History)
1 user (show)

See Also:
Fixed In Version: 5.0.0
Doc Type: Bug Fix
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Last Closed: 2007-01-26 16:33:23 EST
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RHEL 7.3 requirements from Atomic Host:
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Description Stephen Tweedie 2006-12-20 05:33:28 EST
On x86, the virtualised kernel supports a maximum of 16GB of physical memory. 
The x86_64 kernel does not have this limit.
Comment 1 Jan Mark Holzer 2006-12-20 06:30:10 EST
Shouldn't we point out the limit is for the host (dom0/Hypervisor) side as the
guest/domU kernel has (currently) other limitations (x86/2GB and x86_64/4GB) ?
Comment 2 Don Domingo 2006-12-20 17:56:34 EST
release notes contains the following under "Virtualization":

<quote>
At present, the Virtualization feature has the following limitations:

<snip>    

* (x86) Hardware-virtualized guests cannot have more than 2GB of RAM.
* (x86_64) Hardware-virtualized guests cannot have more than 4GB of RAM.

</quote>

as per BZ 218820.

thanks!
Comment 4 Stephen Tweedie 2006-12-21 12:16:59 EST
Yes, but the 16G limit in this release note request is nothing to do with guest
limits --- it's a physical hardware support issue.  The i686 kernel-xen *HOST*
kernel cannot support more than 16GB of physical memory.

I suggest modifying 

* (x86) Hardware-virtualized guests cannot have more than 2GB of RAM.
* (x86_64) Hardware-virtualized guests cannot have more than 4GB of RAM.

to replace "RAM" with "virtual memory" or just "memory" to make this distinction
even clearer (a guest does not use physical RAM when it is saved to disk, for
example.)
Comment 6 Jay Turner 2007-01-26 16:26:26 EST
Confirmed with 20070125.0.
Comment 7 Jay Turner 2007-01-26 16:33:23 EST
Verified in the latest trees.

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