On Wed, Jun 13, 2018 at 10:15:10AM -0400, Yaowei Bai wrote: > On Wed, Jun 13, 2018 at 06:27:49AM -0500, Eric Blake wrote: > > 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 <baiyao...@cmss.chinamobile.com> > > >>--- > > >> 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 invocation > > > > > >The 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_documentation > > > > The 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 > > Yes, this patch is inspired by this situation when translating DPRINT into > trace for a new qemu utility (much like qemu-nbd) following > docs/devel/tracing.txt. > The utility complains it don't support -trace option. So i sent this > patch after confirming this with qemu-nbd,qemu-io utilities. > > > 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. > > Thanks for your nice explaination. If this patch could be merged i will > send V2 with a commit message.
Please update the remaining occurrences of the -trace option syntax in v2: $ git grep -- -trace docs/devel/tracing.txt Stefan
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