Re: armv6-novfp and armv6-vfp and tune files

[Mark Hatle <mark.hatle@windriver.com>]

On 9/17/11 11:13 AM, Denis 'GNUtoo' Carikli wrote:
> hi,
> I've an HTC Dream, it has an armv6 CPU but lack a vfp unit.
> I want to add correct support for it in meta-smartphone/meta-htc.
> In order to have a correct machine config that works a tune inc file
> must be required in it.
> 
> In openembedded-core there is no tune file yet for an armv6 that lacks a
> vfp, but there are theses two files:
> meta/conf/machine/include/tune-arm1136jf-s.inc
> meta/conf/machine/include/arm/arch-armv6.inc
> 
> tune-arm1136jf-s.inc requires arch-armv6.inc.
> 
> So I need to create an tune-arm1136ej-s.inc which requires an
> arch-armv6-novfp.inc(also to be created).
> 

Is the arm1136ej-s the core in the HTC dream?  Or is it a custom armv6 (w/o vfp)?

If it's the later you should add a new tune file for this htc dream's processor.

The arch-armv6 should be modified to include a novfp feature.  Using the armv5
as an example, I suggest:

 # Little Endian
-AVAILTUNES += "armv6 armv6t armv6hf armv6thf"
+AVAILTUNES += "armv6-novfp armv6 armv6t armv6hf armv6thf"

+TUNE_FEATURES_tune-armv6-novfp ?= "armv6"

+PACKAGE_EXTRA_ARCHS_tune-armv6-novfp = "${PACKAGE_EXTRA_ARCHS_tune-armv5e} armv6"

(if there is a thumb variant, add that as well...)

(...and... if there is a big endian variant add that as well...)

Then using tune-arm1136ej-s.inc as a model for a new htc-dream tune:

DEFAULTTUNE ?= "htcdream"

require conf/machine/include/arm/arch-armv6.inc

TUNEVALID[htcdream] = "Enable HTC dream specific processor optimizations"
TUNE_CCARGS += "${@bb.utils.contains("TUNE_FEATURES", "htcdream",
"-mtune=<something appropriate here>", "", d)}"

AVAILTUNES += "htcdream"
TUNE_FEATURES_tune-htcdream = "${TUNE_FEATURES_tune-armv6-novfp} htcdream"
PACKAGE_EXTRA_ARCHS_tune-htcdream = "${PACKAGE_EXTRA_ARCHS_tune-armv6-novfp}"

If the htc-dream has an existing core, then you can simply add a "novfp" variant
to that core.

> 
> however I wonder how to create the armv6-novfp.inc:
> arch-armv6.inc has things like that inside:
> TUNE_FEATURES_tune-armv6 ?= "armv6 vfp"
> or:
> PACKAGE_EXTRA_ARCHS_tune-armv6 = "${PACKAGE_EXTRA_ARCHS_tune-armv5e-vfp}
> armv6-vfp"
> or:
> TUNEVALID[armv6] = "Enable instructions for ARMv6"
> 
> in the recipes and in the feeds and in the workdir it's labeled as
> "armv6-vfp".
> 
> So the correct way would be to label an armv6 that lacks a vfp "armv6".
> 
> however, I fear that the armv6 override is already taken, and also maybe
> the arch-armv6.inc should be moved to arch-armv6-vfp.inc.

Due to the way this was originally implemented, I was told no variants of the
armv6 existed w/o VFP.....  so the naming is what it is, I'm open to suggesting
a change to make it more explicit that armv6 is w/o VFP and armv6-vfp is w/ VFP.
 But it's up to the oe-core community if they'll accept that change to the core
tunings.  It's more likely they will accept armv6-novfp (as in the examples above.)

--Mark

> Denis.
> 
> 
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