From: Wei Liu <wei.liu2@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>,
Wei Liu <wei.liu2@citrix.com>,
xen-devel <xen-devel@lists.xenproject.org>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Subject: Re: [PATCH v2 3/3] xl: new "loglvl" command
Date: Mon, 14 Mar 2016 16:01:24 +0000 [thread overview]
Message-ID: <20160314160124.GB22805@citrix.com> (raw)
In-Reply-To: <56E6EB8702000078000DC214@prv-mh.provo.novell.com>
On Mon, Mar 14, 2016 at 09:49:11AM -0600, Jan Beulich wrote:
> >>> On 14.03.16 at 16:36, <wei.liu2@citrix.com> wrote:
> > On Mon, Mar 14, 2016 at 09:23:35AM -0600, Jan Beulich wrote:
> >> >>> On 08.03.16 at 17:20, <wei.liu2@citrix.com> wrote:
> >> > On Fri, Mar 04, 2016 at 09:48:16AM -0700, Jan Beulich wrote:
> >> >> --- a/tools/libxl/xl_cmdimpl.c
> >> >> +++ b/tools/libxl/xl_cmdimpl.c
> >> >> @@ -6469,6 +6469,84 @@ int main_debug_keys(int argc, char **arg
> >> >> return 0;
> >> >> }
> >> >>
> >> >> +static const struct {
> >> >> + int level;
> >> >> + char string[8];
> >> >> +} loglvls[] = {
> >> >> + { 0, "none" },
> >> >> + { 1, "error" },
> >> >> + { 2, "warning" },
> >> >> + { 3, "info" },
> >> >> + { 4, "all" },
> >> >> + { 4, "debug" },
> >> >
> >> > The semantics of the numbers should go into libxl_types.idl. Maybe
> >> > something like
> >> >
> >> > # Keep in sync with Xen log level.
> >> > libxl_xen_log_level = Enumeration (...);
> >> >
> >> > Then in here
> >> >
> >> > static const struct {
> >> > int level;
> >> > char string[8];
> >> > } loglvls[] = {
> >> > { LIBXL_XEN_LOG_LEVEL_NONE, "none" },
> >> > { ..., "error" },
> >> > { ..., "warning" },
> >> > { ..., "info" },
> >> > { ..., "all" },
> >> > { ..., "debug" },
> >> >
> >> > Please also note that after the introduction of this API, Xen log level
> >> > will become part of the stable API and subject to some compatibility
> >> > constraints. Is this what you wanted?
> >>
> >> No, and I actually I'm having trouble following your request: This
> >> lives in xl_cmdimpl.c, which I didn't think is subject to any stability
> >> requirements in the mapping of strings (from the xl command line)
> >> to numbers. It is _specifically_ that I do not want to fix those
> >> mappings.
> >
> > The new API libxl_log_level relies on the semantics of these mappings.
> > To make the new API useful to all clients, the semantics of log levels
> > needs to go into libxl_types.idl (as mentioned a few lines above), hence
> > it becomes part of the stable API. Otherwise you end up with an API
> > accepting arbitrary magic numbers.
>
> Well - what do you suggest? I'm meanwhile willing to give up on this,
> as baking the mapping into some ABI is clearly not what we should do
> or what I want. Moving the translation into libxl also wouldn't help.
> Which would leave the option of doing this in libxc, but then again I'm
> generally opposed to passing around strings instead of numbers, as
> the latter are better to work with at all layers.
>
I don't have a very clear idea on what to suggest at the moment, sorry.
What kind of changes to xen log level might happen in the future?
Wei.
> Jan
>
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next prev parent reply other threads:[~2016-03-14 16:06 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-04 16:38 [PATCH v2 0/3] allow runtime log level threshold adjustments Jan Beulich
2016-03-04 16:46 ` [PATCH v2 1/3] console: allow " Jan Beulich
2016-03-04 20:55 ` Konrad Rzeszutek Wilk
2016-03-07 10:44 ` Jan Beulich
2016-03-07 14:41 ` Konrad Rzeszutek Wilk
2016-03-07 15:19 ` Jan Beulich
2016-03-04 16:47 ` [PATCH v2 2/3] libxc: wrapper for log level sysctl Jan Beulich
2016-03-05 16:00 ` Dario Faggioli
2016-03-08 16:20 ` Wei Liu
2016-03-04 16:48 ` [PATCH v2 3/3] xl: new "loglvl" command Jan Beulich
2016-03-04 18:45 ` Dario Faggioli
2016-03-07 11:46 ` Jan Beulich
2016-03-07 18:07 ` Dario Faggioli
2016-03-08 8:08 ` Jan Beulich
2016-03-08 14:05 ` George Dunlap
2016-03-08 16:09 ` Wei Liu
2016-03-08 18:05 ` Dario Faggioli
2016-03-05 15:36 ` Dario Faggioli
2016-03-07 13:20 ` Fabio Fantoni
2016-03-07 13:26 ` Jan Beulich
2016-03-08 16:20 ` Wei Liu
2016-03-14 15:23 ` Jan Beulich
2016-03-14 15:36 ` Wei Liu
2016-03-14 15:49 ` Jan Beulich
2016-03-14 16:01 ` Wei Liu [this message]
2016-03-14 17:00 ` Jan Beulich
2016-03-14 17:07 ` Ian Jackson
2016-03-15 7:37 ` Jan Beulich
2016-03-15 13:58 ` Wei Liu
2016-03-15 14:07 ` Jan Beulich
2016-03-15 14:51 ` Wei Liu
2016-03-15 15:03 ` Jan Beulich
2016-03-15 15:38 ` Ian Jackson
2016-03-16 11:22 ` Jan Beulich
2016-04-28 15:33 ` Wei Liu
2016-04-29 7:20 ` Jan Beulich
2016-05-02 11:14 ` Wei Liu
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