Re: [PATCH liburing 0/5] Add basic test for nvme uring passthrough commands

[Kanchan Joshi <joshi.k@samsung.com>]

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On Fri, Aug 12, 2022 at 09:03:12AM -0700, Casey Schaufler wrote:
>On 8/12/2022 8:33 AM, Paul Moore wrote:
>> On Thu, Aug 11, 2022 at 9:51 PM Jens Axboe <axboe@kernel.dk> wrote:
>>> On 8/11/22 6:43 PM, Casey Schaufler wrote:
>>>> On 7/19/2022 6:52 AM, Ankit Kumar wrote:
>>>>> This patchset adds test/io_uring_passthrough.c to submit uring passthrough
>>>>> commands to nvme-ns character device. The uring passthrough was introduced
>>>>> with 5.19 io_uring.
>>>>>
>>>>> To send nvme uring passthrough commands we require helpers to fetch NVMe
>>>>> char device (/dev/ngXnY) specific fields such as namespace id, lba size.
>>>> There wouldn't be a way to run these tests using a more general
>>>> configuration, would there? I spent way too much time trying to
>>>> coax my systems into pretending it has this device.
>>> It's only plumbed up for nvme. Just use qemu with an nvme device?
>>>
>>> -drive id=drv1,if=none,file=nvme.img,aio=io_uring,cache.direct=on,discard=on \
>>> -device nvme,drive=drv1,serial=blah2
>>>
>>> Paul was pondering wiring up a no-op kind of thing for null, though.
>> Yep, I started working on that earlier this week, but I've gotten
>> pulled back into the SCTP stuff to try and sort out something odd.
>>
>> Casey, what I have isn't tested, but I'll toss it into my next kernel
>> build to make sure it at least doesn't crash on boot and if it looks
>> good I'll send it to you off-list.
>
>Super. Playing with qemu configuration always seems to suck time
>and rarely gets me where I want to be.

FWIW, one more option (not easier than no-op/null though) is to emulate
nvme over a regular-file using loopback-fabrics target.
A coarse script is here -
https://github.com/joshkan/loopback-nvme-uring/commit/96853963a196f2d307d4d8e60d1276a08b520307


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