Understanding Bluez mgmt events

Understanding Bluez mgmt events

[Natalya Rozhnova]

Hello,

I'm trying to understand the mgmt events in Bluez.
If I understand correctly, the MGMT_OP_... commands are first sent as following:

mgmt_send(adapter->mgmt, MGMT_OP_START_DISCOVERY, ...)

And then it should trigger a corresponding event like
MGMT_EV_DISCOVERING, MGMT_EV_DEVICE_FOUND etc.

I'm quite lost in understanding who, where and how generates these
MGMT_EV... events...
Could anybody please explain this on a simple example or showing a
piece of code in bluez sources where it is done...

Thanks in advance for any help,
Natalya

Re: Understanding Bluez mgmt events

[Johan Hedberg]

Hi Natalya,

On Tue, May 16, 2017, Natalya Rozhnova wrote:
> I'm trying to understand the mgmt events in Bluez.
> If I understand correctly, the MGMT_OP_... commands are first sent as following:
> 
> mgmt_send(adapter->mgmt, MGMT_OP_START_DISCOVERY, ...)
> 
> And then it should trigger a corresponding event like
> MGMT_EV_DISCOVERING, MGMT_EV_DEVICE_FOUND etc.
> 
> I'm quite lost in understanding who, where and how generates these
> MGMT_EV... events...
> Could anybody please explain this on a simple example or showing a
> piece of code in bluez sources where it is done...

The mgmt protocol is a protocol between user space and the kernel. User
space (normally bluetoothd) sends commands to the kernel, and the kernel
sends events to user space. You can find the kernel-side implementation
in net/bluetooth/mgmt.c.

Johan

Re: Understanding Bluez mgmt events

[Natalya Rozhnova]

Hello Johan,

Thank you very much for your reply, it's much clearer now!

Natalya

2017-05-16 16:24 GMT+02:00 Johan Hedberg <johan.hedberg@gmail.com>:
> Hi Natalya,
>
> On Tue, May 16, 2017, Natalya Rozhnova wrote:
>> I'm trying to understand the mgmt events in Bluez.
>> If I understand correctly, the MGMT_OP_... commands are first sent as following:
>>
>> mgmt_send(adapter->mgmt, MGMT_OP_START_DISCOVERY, ...)
>>
>> And then it should trigger a corresponding event like
>> MGMT_EV_DISCOVERING, MGMT_EV_DEVICE_FOUND etc.
>>
>> I'm quite lost in understanding who, where and how generates these
>> MGMT_EV... events...
>> Could anybody please explain this on a simple example or showing a
>> piece of code in bluez sources where it is done...
>
> The mgmt protocol is a protocol between user space and the kernel. User
> space (normally bluetoothd) sends commands to the kernel, and the kernel
> sends events to user space. You can find the kernel-side implementation
> in net/bluetooth/mgmt.c.
>
> Johan