Re: [Qemu-devel] [PATCH] hw/bt: drop bluetooth keyboard emulation.

[Peter Maydell]

On 12 November 2018 at 09:16, Markus Armbruster <address@hidden> wrote:
> Peter Maydell <address@hidden> writes:
>
>> On 9 November 2018 at 14:14, Gerd Hoffmann <address@hidden> wrote:
>>> Broken (segfaultson first keypress) and appearently unused.
>>>
>>> Signed-off-by: Gerd Hoffmann <address@hidden>
>
> Please show the reproducer in the commit message.  Stack backtrace
> wouldn't hurt.
>
>>> ---
>>>  include/hw/bt.h     |   3 -
>>>  hw/bt/hid.c         | 554 
>>> ----------------------------------------------------
>>>  vl.c                |  34 +---
>>>  hw/bt/Makefile.objs |   3 +-
>>>  qemu-options.hx     |   9 -
>>>  5 files changed, 2 insertions(+), 601 deletions(-)
>>>  delete mode 100644 hw/bt/hid.c
>>
>> Are we definitely happy that all the use cases for
>> this code segfault, not just the one you tested ?
>
> Are there any others?
>
>> Does it cost us much to mark this deprecated in 3.1
>> and drop it in 4.0 ?
>
> The cost is offering a known-to-be-broken option to users.
>
> The other half of the tradeoff: what would it gain us?

My point is that we do not know it to be broken. We know that
it has one bug, in the command line and segfault that Gerd
found. I haven't seen anybody say they've done a check of
all the use cases of this code and confirmed that all of them
must pass through the codepath/situation that segfaults.
What it gains us is that we get to be sure that we are keeping
our promise with our users that we don't just randomly remove
features they were using without notice.

thanks
-- PMM