Re: [libvirt] [PATCH v5 01/11] nvdimm: introduce 'alignsize' element into xml for NVDIMM memory

NVDIMM emulation will mmap the backend file, it uses host pagesize as the alignment of mapping address before, but some backends may require alignments different from the pagesize. So the 'alignsize' option will be introduced to allow users specifying the proper

alignment: <devices> ... <memory model='nvdimm' access='shared'> <source> <path>/dev/dax0.0</path> <alignsize unit='MiB'>2</alignsize> </source> <target> <size unit='MiB'>4094</size> <node>0</node> <label> <size unit='MiB'>2</size> </label> </target> </memory> ... </devices> Signed-off-by: Luyao Zhong <luyao.zhong(a)intel.com&gt; --- docs/formatdomain.html.in | 23 +++++++-- docs/schemas/domaincommon.rng | 13 +++-- src/conf/domain_conf.c | 32 +++++++++--- src/conf/domain_conf.h | 1 + .../memory-hotplug-nvdimm-align.xml | 58 ++++++++++++++++++++++ .../memory-hotplug-nvdimm-align.xml | 1 + tests/qemuxml2xmltest.c | 1 + 7 files changed, 116 insertions(+), 13 deletions(-) create mode 100644 tests/qemuxml2argvdata/memory-hotplug-nvdimm-align.xml create mode 120000 tests/qemuxml2xmloutdata/memory-hotplug-nvdimm-align.xml diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index a18d063..515e656 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -8322,6 +8322,7 @@ qemu-kvm -net nic,model=? /dev/null &lt;memory model='nvdimm'&gt; &lt;source&gt; &lt;path&gt;/tmp/nvdimm&lt;/path&gt; + &lt;alignsize unit='KiB'&gt;2048&lt;/alignsize&gt; &lt;/source&gt; &lt;target&gt; &lt;size unit='KiB'&gt;524288&lt;/size&gt; @@ -8403,10 +8404,26 @@ qemu-kvm -net nic,model=? /dev/null </dl> <p> - For model <code>nvdimm</code> this element is mandatory and has a - single child element <code>path</code> that represents a path - in the host that backs the nvdimm module in the guest. + For model <code>nvdimm</code> this element is mandatory. The + mandatory child element <code>path</code> represents a path in + the host that backs the nvdimm module in the guest. If + <code>nvdimm</code> is provided, then the following optional + elements can be provided as well:

</p> + + <dl> + <dt><code>alignsize</code></dt> + <dd> + <p> + This element can be used to specify a proper alignment. + When mmap(2) the backend files, QEMU uses the host page + size by default as the alignment of mapping address. However, + some backends may require alignments different from the page.

+ For example, mmap a real NVDIMM device maybe 2M-aligned required.