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From: | Eric Blake |
Subject: | Re: [Qemu-devel] [PATCH] tracing.txt: add missing '-' for trace option |
Date: | Wed, 13 Jun 2018 06:27:49 -0500 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 06/12/2018 10:50 PM, Emilio G. Cota wrote:
On Tue, Jun 12, 2018 at 23:15:49 -0400, Yaowei Bai wrote:Signed-off-by: Yaowei Bai <address@hidden> --- docs/devel/tracing.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/devel/tracing.txt b/docs/devel/tracing.txt index 07abbb3..6ab32cc 100644 --- a/docs/devel/tracing.txt +++ b/docs/devel/tracing.txt @@ -18,7 +18,7 @@ for debugging, profiling, and observing execution.3. Run the virtual machine to produce a trace file: - qemu -trace events=/tmp/events ... # your normal QEMU invocation+ qemu --trace events=/tmp/events ... # your normal QEMU invocationThe second dash is not missing; both '-args' and '--args' work. '-args' seems to be favoured though; see `qemu -h' or `qemu --h' :-)
Actually, we're trying to fix that: https://wiki.qemu.org/BiteSizedTasks#Consistent_option_usage_in_documentationThe one-vs-two dash usage is only supported in qemu, not in qemu-nbd or qemu-img (that is, qemu acts as if it uses getopt_long_only(), while the others use getopt_long() - except that we hand-rolled the parser in qemu, meaning you might find quirks where it sometimes doesn't even match getopt_long_only()).
At any rate, since --trace is an option that is supported across multiple binaries, we SHOULD favor the double-dash spelling in our documentation, so that you can consistently reuse the same --trace invocation without worrying whether the binary parses its arguments with getopt_long() (where double is required) or like getopt_long_only() (where the double is optional but supported).
So I'm in favor of this patch, although it may need more of a commit message summarizing the justification I've just pointed you to.
Reviewed-by: Eric Blake <address@hidden> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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