[En-Nut-Discussion] Which is the latest greatest branch

Uwe Bonnes bon at elektron.ikp.physik.tu-darmstadt.de
Sat Aug 18 20:52:46 CEST 2012

>>>>> "Harald" == Harald Kipp <harald.kipp at egnite.de> writes:

    Harald> Hi developers, On 29.10.2011 00:12, Ulrich Prinz wrote:
    >> On 28.10.2011 11:06, Harald Kipp wrote:
    >>> #elif defined(__ARM_ARCH_7M__) #include <arch/armv7_m/arm_7m.h>
    >>  Again: No!
    Harald> ...
    >> So use the names the people know and look for. Use the names that
    >> people know who did not read 1000s of pages of ARM core manuals know
    >> from friends and colleagues.

    Harald> A malicious question: Do you guys still think it was a good idea
    Harald> to create the cm3 directory?

Seeing Cortex M0, Cortes M4 and Cortex M0+ cm3 might not be the smartest
choice, But I think we can live with it.

    Harald> Just wondering why we have Cortex-M4 files in this directory
    Harald> now?

Because Cortex M4 chips are very similar to M3 chip, at least in the
behaviour important for the OS (NVIC/Interrupts, System timer, etc). M4 is
more capable with regard to instructions and has DSP/FPU instructions, but
,beside FPOU capable threads, the OS program code can be the same and only
the compiled should make use of the more capable instructions. M0 is less
capable with regard to instructions, e.g. no bitbanding, but again only a
thing for the compiler to watch out.

Splitting out M4 would nearly be only code duplication, only when somebody
cares for FPU-aware threads things should go in a seperate directory.

Uwe Bonnes                bon at elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

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