docs/system/virtio-pmem.rst: Fix minor style issues

The virtio-pmem documentation has some minor style issues we hadn't
noticed since we weren't rendering it in our docs:

 * Sphinx doesn't complain about overlong title-underlining the
   way it complains about too-short underlining, but it looks odd;
   make the underlines of section headers the right length

 * Indent of paragraphs makes them render as blockquotes;
   remove the indent so they just render as normal text

 * Leading 'o' isn't rst markup, so it just renders as a literal
   "o"; reformat as a subsection heading instead

 * "QEMU" in the document title and section headings are a bit
   odd and unnecessary since this is the QEMU manual; delete
   or rephrase them

 * There's no need to specify what QEMU version the device first
   appeared in.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Pankaj Gupta <pankaj.gupta@cloud.ionos.com>
This commit is contained in:
Peter Maydell 2020-11-12 14:40:36 +00:00
parent 71266bb4e9
commit c5d7cfdaac

View file

@ -1,22 +1,21 @@
======================== ===========
QEMU virtio pmem virtio pmem
======================== ===========
This document explains the setup and usage of the virtio pmem device
which is available since QEMU v4.1.0.
This document explains the setup and usage of the virtio pmem device.
The virtio pmem device is a paravirtualized persistent memory device The virtio pmem device is a paravirtualized persistent memory device
on regular (i.e non-NVDIMM) storage. on regular (i.e non-NVDIMM) storage.
Usecase Usecase
-------- -------
Virtio pmem allows to bypass the guest page cache and directly use Virtio pmem allows to bypass the guest page cache and directly use
host page cache. This reduces guest memory footprint as the host can host page cache. This reduces guest memory footprint as the host can
make efficient memory reclaim decisions under memory pressure. make efficient memory reclaim decisions under memory pressure.
o How does virtio-pmem compare to the nvdimm emulation supported by QEMU? How does virtio-pmem compare to the nvdimm emulation?
-----------------------------------------------------
NVDIMM emulation on regular (i.e. non-NVDIMM) host storage does not NVDIMM emulation on regular (i.e. non-NVDIMM) host storage does not
persist the guest writes as there are no defined semantics in the device persist the guest writes as there are no defined semantics in the device
@ -69,7 +68,8 @@ Guest Data Persistence
a hint to application to perform fsync for write persistence. a hint to application to perform fsync for write persistence.
Limitations Limitations
------------ -----------
- Real nvdimm device backend is not supported. - Real nvdimm device backend is not supported.
- virtio pmem hotunplug is not supported. - virtio pmem hotunplug is not supported.
- ACPI NVDIMM features like regions/namespaces are not supported. - ACPI NVDIMM features like regions/namespaces are not supported.