Bug 848989 - Documentation says filesystem type="ram" size in kibibytes, implementation uses bytes
Documentation says filesystem type="ram" size in kibibytes, implementation us...
Product: Virtualization Tools
Classification: Community
Component: libvirt (Show other bugs)
All Linux
unspecified Severity low
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Assigned To: Libvirt Maintainers
Depends On:
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Reported: 2012-08-16 22:14 EDT by Matt Johnston
Modified: 2014-04-17 09:19 EDT (History)
2 users (show)

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Doc Type: Bug Fix
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Last Closed: 2014-04-17 09:19:08 EDT
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Description Matt Johnston 2012-08-16 22:14:55 EDT
Description of problem:
The documentation for filesystem type="ram" (http://libvirt.org/formatdomain.html) says size is kibibytes, it's actually interpreted as bytes:

File used for "virsh define":
    <filesystem type='ram'>
      <source usage='10000000'/>
      <target dir='/mnt/share'/>

In the container:
$ df -h /mnt/share/
Filesystem            Size  Used Avail Use% Mounted on
tmpfs                 9.6M     0  9.6M   0% /mnt

Output of "virsh edit":
    <filesystem type='ram' accessmode='passthrough'>
      <source usage='9' units='KiB'/>
      <target dir='/mnt/share'/>

Additional info:
libvirt 0.9.14 on centos 6.2, Linux 3.2.6
Comment 1 Ján Tomko 2014-04-17 09:19:08 EDT
Fixed upstream by:
commit 3f029fb5319b9dc9cc2fbf8d1ba4505ee9e4b1e3
Author:     Ján Tomko <jtomko@redhat.com>
AuthorDate: 2013-10-09 14:17:13 +0200
Commit:     Ján Tomko <jtomko@redhat.com>
CommitDate: 2013-10-09 17:44:45 +0200

    LXC: Fix handling of RAM filesystem size units
    Since 76b644c when the support for RAM filesystems was introduced,
    libvirt accepted the following XML:
    <source usage='1024' unit='KiB'/>
    This was parsed correctly and internally stored in bytes, but it
    was formatted as (with an extra 's'):
    <source usage='1024' units='KiB'/>
    When read again, this was treated as if the units were missing,
    meaning libvirt was unable to parse its own XML correctly.
    The usage attribute was documented as being in KiB, but it was not
    scaled if the unit was missing. Transient domains still worked,
    because this was balanced by an extra 'k' in the mount options.
    This patch:
    Changes the parser to use 'units' instead of 'unit', as the latter
    was never documented (fixing persistent domains) and some programs
    (libvirt-glib, libvirt-sandbox) already parse the 'units' attribute.
    Removes the extra 'k' from the tmpfs mount options, which is needed
    because now we parse our own XML correctly.
    Changes the default input unit to KiB to match documentation, fixing:

git describe: v1.1.3-77-g3f029fb contains: v1.1.4-rc1~156

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