Return-Path: MIME-Version: 1.0 In-Reply-To: <47E39EED-4F96-4128-BAD1-09CDE4FC7A2E@holtmann.org> References: <20170901080744.11544-1-andrzej.kaczmarek@codecoup.pl> <47E39EED-4F96-4128-BAD1-09CDE4FC7A2E@holtmann.org> From: Andrzej Kaczmarek Date: Fri, 1 Sep 2017 15:28:27 +0200 Message-ID: Subject: Re: [PATCH 1/2] doc/btsnoop: Add nop opcode To: Marcel Holtmann Cc: linux-bluetooth@vger.kernel.org Content-Type: text/plain; charset="UTF-8" List-ID: Hi Marcel, On Fri, Sep 1, 2017 at 2:29 PM, Marcel Holtmann wrote: > Hi Andrzej, > >> This adds 'no operation' opcode for the cases where we do not want to >> include any particular payload, just the header is valid. >> >> For example, when some packets are dropped over TTY implementation can >> pass this information only in some other packet and this won't happen >> until there's actually something to send. With this addition it can >> just send nop after some time to indicate there were packets dropped. >> --- >> doc/btsnoop.txt | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/doc/btsnoop.txt b/doc/btsnoop.txt >> index 975a53f6d..865b81554 100644 >> --- a/doc/btsnoop.txt >> +++ b/doc/btsnoop.txt >> @@ -115,6 +115,13 @@ User Logging >> >> User logging information. >> >> +NOP >> +----------- >> + >> + Code: 0xffff >> + >> + No operation. >> + > > Hmmm. I am not a huge fan of this. Then I see that we defined the ext_hdr that allows to deal with the dropped packets. > > I need to think about this a bit since there are some other opcode extensions we have to do for certain cases where we have unexpected packets. Right now I would propose to use vendor diagnostic or system note with empty payload. Vendor diagnostic would produce a message in btmon which may be misleading and system note with empty payload will print some garbage (i.e. previous contents of buffer) since message is not null-terminated. But in this case I can just fix btmon to skip system notes with no payload and it will be basically the same as nop - does it sound good enough for now? > Regards > > Marcel Best regards, Andrzej