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Re: [Qemu-devel] [RFC/PATCHSET 0/7] virtio: Implement virtio pstore devi
Michael S. Tsirkin
Re: [Qemu-devel] [RFC/PATCHSET 0/7] virtio: Implement virtio pstore device (v2)
Thu, 28 Jul 2016 01:18:42 +0300
On Thu, Jul 28, 2016 at 12:08:24AM +0900, Namhyung Kim wrote:
> This is v2 of the virtio-pstore work. In this patchset I addressed
> most of feedbacks from previous version. Limiting disk size is not
> implemented yet.
For some reason, only parts of the patchset were received.
Pls post all patches to all lists.
If you are changing the virtio interface with host,
like a new device, they you must copy the virtio TC
so make sure there are no objections from there.
> * changes in v2)
> - update VIRTIO_ID_PSTORE to 22 (Cornelia, Stefan)
> - make buffer size configurable (Cornelia)
> - support PSTORE_TYPE_CONSOLE (Kees)
> - use separate virtqueues for read and write
> - support concurrent async write
> - manage pstore (file) id in device side
> - fix various mistakes in qemu device (Stefan)
> It started from the fact that dumping ftrace buffer at kernel
> oops/panic takes too much time. Although there's a way to reduce the
> size of the original data, sometimes I want to have the information as
> many as possible. Maybe kexec/kdump can solve this problem but it
> consumes some portion of guest memory so I'd like to avoid it. And I
> know the qemu + crashtool can dump and analyze the whole guest memory
> including the ftrace buffer without wasting guest memory, but it adds
> one more layer and has some limitation as an out-of-tree tool like not
> being in sync with the kernel changes.
> So I think it'd be great using the pstore interface to dump guest
> kernel data on the host. One can read the data on the host directly
> or on the guest (at the next boot) using pstore filesystem as usual.
> While this patchset only implements dumping kernel log buffer, it can
> be extended to have ftrace buffer and probably some more..
> The patch 0001-0003 are preparation for pstore to support virtio
> device which requires async write. The patch 0004 implements virtio
> pstore driver. It has two virt queue for (sync) read and (async)
> write, pstore buffer and io request and response structure. The
> virtio_pstore_req struct is to give information about the current
> pstore operation. The result will be written to the virtio_pstore_res
> struct. For read operation it also uses virtio_pstore_fileinfo struct.
> The patch 0005 adds support for PSTORE_TYPE_CONSOLE which was
> requested by Kees. The console data is appended to a single file for
> The patch 0006 and 0007 implement virtio-pstore legacy PCI device on
> qemu-kvm and kvmtool respectively. I referenced virtio-baloon and
> virtio-rng implementations and I don't know whether kvmtool supports
> modern virtio 1.0+ spec. Other transports might be supported later.
> For example, using virtio-pstore on qemu looks like below:
> $ qemu-system-x86_64 -enable-kvm -device virtio-pstore,directory=xxx
> When guest kernel gets panic the log messages will be saved under the
> xxx directory.
> $ ls xxx
> dmesg-1.enc.z dmesg-2.enc.z
> As you can see the pstore subsystem compresses the log data using zlib
> (now supports lzo and lz4 too). The data can be extracted with the
> following command:
> $ cat xxx/dmesg-1.enc.z | \
> > python -c 'import sys, zlib; print(zlib.decompress(sys.stdin.read()))'
> Oops#1 Part1
> <5>[ 0.000000] Linux version 4.6.0kvm+ (address@hidden) (gcc version
> 5.3.0 (GCC) ) #145 SMP Mon Jul 18 10:22:45 KST 2016
> <6>[ 0.000000] Command line: root=/dev/vda console=ttyS0
> <6>[ 0.000000] x86/fpu: Legacy x87 FPU detected.
> <6>[ 0.000000] x86/fpu: Using 'eager' FPU context switches.
> <6>[ 0.000000] e820: BIOS-provided physical RAM map:
> <6>[ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff]
> <6>[ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff]
> <6>[ 0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff]
> <6>[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x0000000007fddfff]
> <6>[ 0.000000] BIOS-e820: [mem 0x0000000007fde000-0x0000000007ffffff]
> <6>[ 0.000000] BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff]
> <6>[ 0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff]
> <6>[ 0.000000] NX (Execute Disable) protection: active
> <6>[ 0.000000] SMBIOS 2.8 present.
> <7>[ 0.000000] DMI: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
> To enable PSTORE_TYPE_CONSOLE, add 'console=true' to virtio-pstore
> device option. Also 'bufsize' option can set different size for
> pstore buffer (default is 16K). Maybe we can add a config option to
> control the compression later.
> Currently the kvmtool doesn't support any options except the directory
> the pstore saves the logs.
> Namhyung Kim (7):
> pstore: Split pstore fragile flags
> pstore/ram: Set pstore flags dynamically
> pstore: Manage buffer position for async write
> virtio: Basic implementation of virtio pstore driver
> virtio-pstore: Support PSTORE_TYPE_CONSOLE
> qemu: Implement virtio-pstore device
> kvmtool: Implement virtio-pstore device
> drivers/acpi/apei/erst.c | 2 +-
> drivers/firmware/efi/efi-pstore.c | 4 +-
> drivers/virtio/Kconfig | 10 +
> drivers/virtio/Makefile | 1 +
> drivers/virtio/virtio_pstore.c | 421 +++++++++++++++++++++
> fs/pstore/platform.c | 65 +++-
> fs/pstore/ram.c | 8 +
> include/linux/pstore.h | 9 +-
> include/uapi/linux/Kbuild | 1 +
> include/uapi/linux/virtio_ids.h | 1 +
> include/uapi/linux/virtio_pstore.h | 78 +++-
> 11 files changed, 580 insertions(+), 20 deletions(-)
> create mode 100644 drivers/virtio/virtio_pstore.c
> create mode 100644 include/uapi/linux/virtio_pstore.h
> Cc: Paolo Bonzini <address@hidden>
> Cc: Radim Krčmář <address@hidden>
> Cc: "Michael S. Tsirkin" <address@hidden>
> Cc: Anthony Liguori <address@hidden>
> Cc: Anton Vorontsov <address@hidden>
> Cc: Colin Cross <address@hidden>
> Cc: Kees Cook <address@hidden>
> Cc: Tony Luck <address@hidden>
> Cc: Steven Rostedt <address@hidden>
> Cc: Ingo Molnar <address@hidden>
> Cc: Minchan Kim <address@hidden>
> Cc: Will Deacon <address@hidden>
> Cc: address@hidden
> Cc: address@hidden
> Cc: address@hidden
> Virtualization mailing list
[Qemu-devel] [PATCH 7/7] kvmtool: Implement virtio-pstore device, Namhyung Kim, 2016/07/27
Re: [Qemu-devel] [RFC/PATCHSET 0/7] virtio: Implement virtio pstore device (v2),
Michael S. Tsirkin <=