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From:   Alain Michaud <alainmichaud@google.com>
Date:   Tue, 21 Jan 2020 13:25:18 -0500
Message-ID: <CALWDO_WyZUvkOgXVSd12q7Trg_=LqSb9KQsXH9_C_k8_kD0ddQ@mail.gmail.com>
Subject: Re: [Bluez PATCH] doc: Add definition for Set Kernel Debug Level
To:     Marcel Holtmann <marcel@holtmann.org>
Cc:     Alain Michaud <alainm@chromium.org>,
        BlueZ <linux-bluetooth@vger.kernel.org>
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Hi Marcel,

I'm not familiar with the dynamic_debug feature.

On ChromiumOS, the interface proposed here is used by the user
feedback system to allow the collection of BT_DBG output when the user
is trying to send us feedback.  If there is a better way to do this,
we can certainly use that. but may need to be pointed in the right
direction.

Thanks,
Alain


On Tue, Jan 21, 2020 at 11:20 AM Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Hi Alain,
>
> > This command is used to by higher level applications to dynamically
> > control the debug logging level of the kernel module.  This is
> > particularly useful to collect debug information from customers filing
> > feedback reports for issues that are difficult to reproduce outside of a
> > customer's particular environement.
> >
> > ---
> >
> > doc/mgmt-api.txt | 25 +++++++++++++++++++++++++
> > 1 file changed, 25 insertions(+)
> >
> > diff --git a/doc/mgmt-api.txt b/doc/mgmt-api.txt
> > index 1e59acc54..f2dba64d1 100644
> > --- a/doc/mgmt-api.txt
> > +++ b/doc/mgmt-api.txt
> > @@ -3047,6 +3047,31 @@ Load Blocked Keys Command
> >       Possible errors:        Invalid Parameters
> >                               Invalid Index
> >
> > +Set Kernel Debug Logging Level Command
> > +=======================
> > +
> > +     Command Code:           0x0047
> > +     Controller Index: <controller id>
> > +     Command Parameters : Debug_Logging_Level (1 octet)
> > +
> > +     This command is used to set the kernel debug logging level. This
> > +     can be by higher level applications to facilitate dynamically
> > +     controlling     the logging level produced by the Bluez kernel module.
> > +
> > +     Supported Debug_Logging_Level values:
> > +             0 : No Logging
> > +             1 : All debug information.
> > +             All other values are reserved for future use.
> > +
> > +     When the kernel receives a value higher than the maximum supported
> > +     value, the kernel module shall set it's logging level to the highest
> > +     value it supports.
> > +
> > +     This command generates a Command Complete event on success or
> > +     a Command Status event on failure.
> > +
> > +     Possible errors:        Invalid Parameters
> > +                             Invalid Index
>
> I need a bit more explanation on how this is suppose to work and why the current dynamic_debug feature is not enough.
>
> Regards
>
> Marcel
>