Re: [Qemu-devel] Patch to add helpful tracing output for driver authors in NVMe emulation

[Eric Blake <eblake@redhat.com>]

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On 10/07/2017 02:51 AM, Doug Gale wrote:
> Completely re-implemented patch, with significant improvements (now
> specifies values in several places I missed, also reduced the amount
> of redundant lines). I used the nvme_ as the tracing infrastructure
> prefix. Tested with -trace nvme_* on the qemu command line, worked for
> me.

This information belongs...

> 
>>From 166f57458d60d363a10a0933c3e860985531ac96 Mon Sep 17 00:00:00 2001
> From: Doug Gale <doug16k@gmail.com>
> Date: Thu, 5 Oct 2017 19:02:03 -0400
> Subject: [PATCH] Add tracing output to NVMe emulation to help driver authors.
> 
> This uses the tracing infrastructure using nvme_ as the prefix.
> 
> Signed-off-by: Doug Gale <doug16k@gmail.com>
> ---

...here, after the --- separator.  It is useful to the patch reviewer,
but does not need to be in the 'git log' history.  The maintainers use
'git am' to process incoming patches, which automatically prunes review
comments located in this location.

Also, since this is a version 2 patch, it is best if your subject line
includes 'v2', and if you send the patch as a new top-level thread
rather than in-reply-to v1.  This can be done with 'git send-email -v2'.

The subject line is atypical; we tend to prefer 'topic: Short summary',
where you are missing the topic, you had a trailing dot that is not
typical, and where your line is longer than usual.  A better subject
line might be:

nvme: Add tracing output


For more helpful information on patch submission:

https://wiki.qemu.org/Contribute/SubmitAPatch

I didn't look closely at the patch itself, but did notice:

> +nvme_mmio_start_failed(void) "setting controller enable bit failed!"
> +nvme_mmio_start_success(void) "setting controller enable bit succeeded"
> +nvme_mmio_stopped(void) "cleared controller enable bit"
> +nvme_mmio_shutdown_set(void) "shutdown bit set"
> +nvme_mmio_shutdown_cleared(void) "shutdown bit cleared"
> +nvme_mmio_ignored(uint64_t offset, uint64_t data) "invalid MMIO
> write, offset=0x%"PRIx64", data=%"PRIx64"!"

You have a couple of traces with a trailing '!'; that is atypical,
because we don't need our traces to shout at the user.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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