[ECOS] What does "Enable Thumb instructions" do?

[ECOS] What does "Enable Thumb instructions" do?

[Lewin A.R.W. Edwards]

Hi all,

What does the option "enable thumb instructions" actually do? At least for 
the Cirrus EDB7212 target, this ecc option doesn't seem to change any 
compiler switches or affect the code size at all.
=== Lewin A.R.W. Edwards (Embedded Engineer)
Work: http://www.digi-frame.com/
Personal: http://www.zws.com/ and http://www.larwe.com/

"Und setzet ihr nicht das Leben ein,
Nie wird euch das Leben gewonnen sein."

Re: [ECOS] What does "Enable Thumb instructions" do?

[Jesper Skov]

>>>>> "Lewin" == Lewin A R W Edwards <larwe@larwe.com> writes:

Lewin> Hi all, What does the option "enable thumb instructions"
Lewin> actually do? At least for the Cirrus EDB7212 target, this ecc
Lewin> option doesn't seem to change any compiler switches or affect
Lewin> the code size at all.

Probably because there has not been any incentive to test thumb on
that platform. Look at the PID CDL to see how to deal with the option.

Jesper

Re: [ECOS] What does "Enable Thumb instructions" do?

[Lewin A.R.W. Edwards]

>Lewin> Hi all, What does the option "enable thumb instructions"
>Lewin> actually do? At least for the Cirrus EDB7212 target, this ecc
>
>Probably because there has not been any incentive to test thumb on
>that platform. Look at the PID CDL to see how to deal with the option.

In 1.3.1 (and... just checked... current CVS too) it seems to just change 
the tool prefix to "thumb-elf" instead of "arm-elf", which is no longer 
supported. Also it adds the -mthumb-interwork switch.

So I guess thumb is just broken at all levels right now.

=== Lewin A.R.W. Edwards (Embedded Engineer)
Work: http://www.digi-frame.com/
Personal: http://www.zws.com/ and http://www.larwe.com/

"Und setzet ihr nicht das Leben ein,
Nie wird euch das Leben gewonnen sein."

Re: [ECOS] What does "Enable Thumb instructions" do?

[Jesper Skov]

>>>>> "Lewin" == Lewin A R W Edwards <larwe@larwe.com> writes:

Lewin> In 1.3.1 (and... just checked... current CVS too) it seems to
Lewin> just change the tool prefix to "thumb-elf" instead of
Lewin> "arm-elf", which is no longer supported. Also it adds the
Lewin> -mthumb-interwork switch.

Lewin> So I guess thumb is just broken at all levels right now.

No, we use thumb-elf tools locally. Stuff works fine, to the best of
my knowledge.

Yes, it may not build for people using more recent tools. But the
support is there. It's just a question of using the correct runes to
get it going.  Those runes are what I referred to in the PID
CDL. Clone that, but replace thumb-elf- with appropriate -m<options>
and you should be set.

Jesper