Re: [PATCH 00/14] Initial BPF-JIT support for MIPS

[Markos Chandras <Markos.Chandras@imgtec.com>]

Hi Jonas,

On 04/09/2014 11:11 AM, Jonas Gorski wrote:
> On Wed, Apr 9, 2014 at 10:55 AM, Markos Chandras
> <Markos.Chandras@imgtec.com> wrote:
>> I used in fact only R2 devices. I also use R2 specific instructions such as
>> "ins" and "wsbh". I haven't really considered supporting older ISAs for a
>> couple of reasons. R2 has been around for a long time so a ~7y old device is
>> probably R2 capable. Furthermore, I was not sure whether mips32/64R1 devices
>> are likely to run the latest kernel (and/or use BPF-JIT at all). But I could
>> easily be wrong.
>> Having said that, it's possible to support R1 devices but I'd like to avoid
>> the overhead so a few #ifdefs are needed in the code. My personal preference
>> is to support R2 in the initial patch, and add R1 support later on (along
>> with the optimizations I have in mind).
>
> As far as I can tell on a first glance, you are only using "wsbh", and
> only if the device is running little endian. There is code to emit
> "ins", but it isn't evoked from anywhere.

You are right. Seems like a leftover while I was playing with different 
implementations. I will drop it. Regarding the wsbh, I assume a few ORs 
and shifts will emulate the wsbh instruction for R1. I will have a look 
and provide a v2 soon.

-- 
markos