Re: [PATCH 1/3] virtio: Basic implementation of virtio pstore driver

From: Paolo Bonzini <pbonzini@redhat.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	virtio-dev@lists.oasis-open.org,
	"Tony Luck" <tony.luck@intel.com>,
	"Kees Cook" <keescook@chromium.org>,
	kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
	"Anton Vorontsov" <anton@enomsg.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	qemu-devel@nongnu.org, "Minchan Kim" <minchan@kernel.org>,
	"Anthony Liguori" <aliguori@amazon.com>,
	"Colin Cross" <ccross@android.com>,
	virtualization@lists.linux-foundation.org,
	"Ingo Molnar" <mingo@kernel.org>
Subject: Re: [PATCH 1/3] virtio: Basic implementation of virtio pstore driver
Date: Tue, 15 Nov 2016 15:38:42 +0100	[thread overview]
Message-ID: <a6fc0acb-6ecc-a184-9e06-e76c7398fc08@redhat.com> (raw)
In-Reply-To: <20161115143629.GA29740@danjae.aot.lge.com>

On 15/11/2016 15:36, Namhyung Kim wrote:
> Hi,
> 
> On Tue, Nov 15, 2016 at 10:57:29AM +0100, Paolo Bonzini wrote:
>>
>>
>> On 15/11/2016 06:06, Michael S. Tsirkin wrote:
>>> On Tue, Nov 15, 2016 at 01:50:21PM +0900, Namhyung Kim wrote:
>>>> Hi Michael,
>>>>
>>>> On Thu, Nov 10, 2016 at 06:39:55PM +0200, Michael S. Tsirkin wrote:
>>>>> On Sat, Aug 20, 2016 at 05:07:42PM +0900, Namhyung Kim wrote:
>>>>>> The virtio pstore driver provides interface to the pstore subsystem so
>>>>>> that the guest kernel's log/dump message can be saved on the host
>>>>>> machine.  Users can access the log file directly on the host, or on the
>>>>>> guest at the next boot using pstore filesystem.  It currently deals with
>>>>>> kernel log (printk) buffer only, but we can extend it to have other
>>>>>> information (like ftrace dump) later.
>>>>>>
>>>>>> It supports legacy PCI device using single order-2 page buffer.
>>>>>
>>>>> Do you mean a legacy virtio device? I don't see why
>>>>> you would want to support pre-1.0 mode.
>>>>> If you drop that, you can drop all cpu_to_virtio things
>>>>> and just use __le accessors.
>>>>
>>>> I was thinking about the kvmtools which lacks 1.0 support AFAIK.
>>>
>>> Unless kvmtools wants to be left behind it has to go 1.0.
>>
>> And it also has to go ACPI.  Is there any reason, apart from kvmtool, to
>> make a completely new virtio device, with no support in existing guests,
>> rather than implement ACPI ERST?
> 
> Well, I know nothing about ACPI.  It looks like a huge spec and I
> don't want to dig into it just for this.

ERST (error record serialization table) is a small subset of the ACPI spec.

Paolo