[yocto] Tune qemuarm settings and build everything except the kernel?

[Khem Raj]

Hi Evade,

Glad it worked for you at first go. Thats quite an achievement for yocto

On Fri, Aug 31, 2012 at 2:58 PM, Evade Flow <evadeflow at gmail.com> wrote:
>
> Now I'm wondering: is there any easy way to optimize for the actual
> target(s) a bit more than the qemuarm MACHINE type does?  The example
> Makefiles for the old project all contain this line:
>
>    CFLAGS = -g -mcpu=arm1136jf-s -O2 -pipe
>
> What's the best way to arrange for that '-mcpu' option to be used by all
> recipes? Also, are there other optimizations I should consider?  I'm
> appending some details about the board in question, as well as the
> complete output from booting it to a prompt. I'd be ever so grateful if
> someone could recommend sensible base settings for this system, and
> explain how to create a Poky 'layer', or 'machine'---or whatever the
> right nomenclature is---to apply these settings.
>
> Sorry for the long post, and thanks in advance for any advice!
>
>
> ----------
>
> ~ # uname -a
> Linux localhost 2.6.36.2-WR3.0.2ax_standard #1 SMP PREEMPT Wed Oct 19 21:58:54
> EEST 2011 armv7l armv7l armv7l GNU/Linux ODBP D1.0.1 (10.11.2011)
>
> ~ # cat /proc/cpuinfo
> Processor       : ARMv7 Processor rev 0 (v7l)
> processor       : 0
> BogoMIPS        : 1795.68
>
> Features        : swp half thumb fastmult vfp edsp vfpv3 vfpv3d16


I am guessing its some sort of Tegra CPU which had FPU but no neon unit
there is rich set of tuning available for arm.

So you would create  configuration file for your machine. May be just
start by making a copy of
qemuarm.conf

then you would select the right tuning

require conf/machine/include/tune-arm926ejs.inc currently select arm926
you might want something more appropriate.

add
conf/machine/include/tune-arm1136jf-s.inc

this will get to what you had in old project

and you can also go a step further and make it more appropriate for
tegra cpu that you have
we dont have default tunes available readily that are good for tegra
but its not hard to create one

Look at

e.g on tune-cortexa9.inc

you would create something similar for your cpu and then select proper
default tunings.

Have fun

-Khem