On Tue, Jun 9, 2009 at 12:29 PM, Hiroshi DOYU<hiroshi.d...@nokia.com> wrote:
> From: ext Felipe Contreras <felipe.contre...@gmail.com>
> Subject: Re: [PATCH] DSPBRIDGE: Compiler wanrning fix for unlocked_ioctl
> Date: Tue, 9 Jun 2009 11:16:52 +0200
>
>> On Tue, Jun 9, 2009 at 10:02 AM, Hiroshi DOYU<hiroshi.d...@nokia.com> wrote:
>> > From: "ext Kanigeri, Hari" <h-kanige...@ti.com>
>> > Subject: RE: [PATCH] DSPBRIDGE: Compiler wanrning fix for unlocked_ioctl
>> > Date: Mon, 8 Jun 2009 22:49:21 +0200
>> >
>> >> Hi Doyu-san,
>> >>
>> >> Regarding
>> >>
>> >> > http://marc.info/?l=linux-omap&m=124201773423892&w=2
>> >> > I think that the first one should be merged into d.o-z.org now, but
>> >> > for the second one about 128 byte alignment. let me know your
>> >> > thought/plan on it.
>> >>
>> >> -- I think you sent this patch as a probable fix for the slab
>> >> corruption that was observed in Bridge driver, but then we found
>> >> that slab corruption was due to some other issue in Bridge driver
>> >> and not due to the cache alignment.
>> >>
>> >> Irrespective of above point, I think it is good to enforce the cache
>> >> alignment check, but I think the check should be in Proc Map
>> >> function and to start with the check should be under a flag so as
>> >> not to affect some MM applications that use padding to get over the
>> >> alignment issue.
>> >
>> > I think that having configurable option may be reasonable practically,
>> > at the moment.
>> >
>> > But how about the longer term solution? Do you have any plan on how to
>> > deal with this? (ex: TI's OMX layer and some other userland client) Do
>> > you continue the userland buffer padding solution for the futer
>> > release?
>>
>> I don't know about TI's OMX layer, but I'm working on some direct
>> GStreamer wrappers that already do the proper alignment.
>
> I expect that it will bring huge performance benfit.

You mean because of the alignment or because of the implementation? In
any case, you are correct :)

>> My plan currently is to keep working on gst-dsp until we have all the
>> elements we need. After that's done we will be able to turn on the
>> check in the kernel.
>>
>> Then, if I have time I might port the changes to TI's omx il.
>
> Both would be necessary for real products.

IMHO much more would be necessary for real products. Right now the DSP
SW can read/write any location of memory (security risk?), I think all
the memory should be protected and then the bridgedriver should give
the DSP permissions on certain memory areas.

-- 
Felipe Contreras
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