Re: [avr-libc-dev] Hint For Watchdog Disable on Newer AVRs in the Manual

[Joerg Wunsch]

As Harald Kipp wrote:

> No idea what __init() is intended to do, but it won't help: No
> initialized stack pointer, no return.

__init() is the name of the routine jumped to from the reset vector.
crtXXX.o provides a default implementation which is marked weak, so
you could overlay it by your own.  But in that case, you have to take
care about everything the existing __init() takes care about.

> Using any earlier section than .init3 provides another problem: No
> initialized __zero_reg__, no MCUSR or watchdog clear.

Right, that's exactly the reason why typical user startup stuff better
goes to .init3.

> To avoid overriding the mirror variable, I added an attribute to it.

> u_char mcusr_mirror __attribute__ ((section (".noinit")));

> I'd suggest to add this to the watchdog section of the manual.

Yes, that has been left out by accident.  Could you please fill in a
bug report for this, so it won't be forgotten about?

What I don't quite understand, why does it not work for you to have
that code in .init3?  After all, .init2 only contains clearing
__zero_reg__, and the initialization of the stack pointer, so I don't
really see why that should get you at risk with the default ~ 15 ms
watchdog timer.  (Unless you've got loads of code in .init1, of
course.)

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)