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Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver
From: |
Pankaj Gupta |
Subject: |
Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver |
Date: |
Thu, 12 Oct 2017 18:52:45 -0400 (EDT) |
> > > wrote:
> > > >
> > > > > > This patch adds virtio-pmem driver for KVM guest.
> > > > > > Guest reads the persistent memory range information
> > > > > > over virtio bus from Qemu and reserves the range
> > > > > > as persistent memory. Guest also allocates a block
> > > > > > device corresponding to the pmem range which later
> > > > > > can be accessed with DAX compatible file systems.
> > > > > > Idea is to use the virtio channel between guest and
> > > > > > host to perform the block device flush for guest pmem
> > > > > > DAX device.
> > > > > >
> > > > > > There is work to do including DAX file system support
> > > > > > and other advanced features.
> > > > > >
> > > > > > Signed-off-by: Pankaj Gupta <address@hidden>
> > > > > > ---
> > > > > > drivers/virtio/Kconfig | 10 ++
> > > > > > drivers/virtio/Makefile | 1 +
> > > > > > drivers/virtio/virtio_pmem.c | 322
> > > > > > +++++++++++++++++++++++++++++++++++++++
> > > > > > include/uapi/linux/virtio_pmem.h | 55 +++++++
> > > > > > 4 files changed, 388 insertions(+)
> > > > > > create mode 100644 drivers/virtio/virtio_pmem.c
> > > > > > create mode 100644 include/uapi/linux/virtio_pmem.h
> > > > > >
> > > > > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> > > > > > index cff773f15b7e..0192c4bda54b 100644
> > > > > > --- a/drivers/virtio/Kconfig
> > > > > > +++ b/drivers/virtio/Kconfig
> > > > > > @@ -38,6 +38,16 @@ config VIRTIO_PCI_LEGACY
> > > > > >
> > > > > > If unsure, say Y.
> > > > > >
> > > > > > +config VIRTIO_PMEM
> > > > > > + tristate "Virtio pmem driver"
> > > > > > + depends on VIRTIO
> > > > > > + ---help---
> > > > > > + This driver adds persistent memory range within a
> > > > > > KVM guest.
>
> With "Virtio Block Backed Pmem" we could name the config
> option VIRTIO_BLOCK_PMEM
>
> The documentation text could make it clear to people that the
> image shows up as a disk image on the host, but as a pmem
> memory range in the guest.
>
> > > > > I think we need to call this something other than persistent
> > > > > memory to
> > > > > make it clear that this not memory where the persistence can be
> > > > > managed from userspace. The persistence point always requires
> > > > >
> > > So currently /proc/iomem in a guest with a pmem device attached to
> > > a
> > > namespace looks like this:
> > >
> > > c00000000-13bfffffff : Persistent Memory
> > > c00000000-13bfffffff : namespace2.0
> > >
> > > Can we call it "Virtio Shared Memory" to make it clear it is a
> > > different beast than typical "Persistent Memory"? You can likely
> >
> > I think somewhere we need persistent keyword 'Virtio Persistent
> > Memory' or
> > so.
>
> Still hoping for better ideas than "Virtio Block Backed Pmem" :)
>
Dan,
I have a query regarding below patch [*]. My assumption is its halted
because of memory hotplug restructuring work? Anything I am missing
here?
[*] https://www.mail-archive.com/address@hidden/msg02978.html
- [Qemu-devel] [RFC 1/2] pmem: Move reusable code to base header files, (continued)
- [Qemu-devel] [RFC 1/2] pmem: Move reusable code to base header files, Pankaj Gupta, 2017/10/12
- [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Pankaj Gupta, 2017/10/12
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Dan Williams, 2017/10/12
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Pankaj Gupta, 2017/10/12
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Dan Williams, 2017/10/12
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Pankaj Gupta, 2017/10/12
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Rik van Riel, 2017/10/12
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Pankaj Gupta, 2017/10/12
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver,
Pankaj Gupta <=
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Dan Williams, 2017/10/12
- Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Pankaj Gupta, 2017/10/12
Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Stefan Hajnoczi, 2017/10/13
Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Dan Williams, 2017/10/13
Re: [Qemu-devel] [RFC 2/2] KVM: add virtio-pmem driver, Christoph Hellwig, 2017/10/17