Re: [avr-gcc-list] Advice on R_AVR_13_PCREL errors linkingforTiny85_and_ Mega168?!

[Bill Roy]

Hi, Eric:

Hey, virtually a neighbor.  You folks have had quite a winter up there  
in the hills.  Please keep sending the water ;)

And as for the fix: thank you and wow.  The explanation matches  
certain dark speculations I had while watching the linker complain.   
Now I guess I'm off to figure out how to build binutils... will report  
back on how it works out.

And Bitlash flashed its first LED on the Tiny85 as a result of that  
pixie-dust link working.  Now the work begins...

Cheers, and thanks,

-br


Well I don't know whether to be more impresse
On Jan 30, 2009, at 6:01 PM, Weddington, Eric wrote:

> > -----Original Message-----
> > From:
> > address@hidden
> > [mailto:address@hidden
> > org] On Behalf Of Bill Roy
> > Sent: Friday, January 30, 2009 5:37 PM
> > To: address@hidden
> > Subject: Re: [avr-gcc-list] Advice on R_AVR_13_PCREL errors
> > linkingforTiny85_and_ Mega168?!
> >
> > Hi, Eric:
> >
> > Thanks for your kind followup.  Here's the state of play as the sun
> > sets in Denver.
>
> Hey, I'm west of the Springs up at 8500 feet in the mountains. ;-)  
> Used to live in the mountains west of Denver.
>
> > Still puzzled here.
> <snip>
> > firmware bill$ make clean hex
> > rm -f main.hex main.lst main.obj main.cof main.list main.map
> > main.eep.hex main.elf *.o usbdrv/*.o main.s usbdrv/oddebug.s usbdrv/
> > usbdrv.s *.lst
> > avr-gcc -Wall -Os -DF_CPU=16500000 -Iusbdrv -I. -DDEBUG_LEVEL=0 -
> > mmcu=attiny85
>
> Ok, stop right there.
>
> It just so happens that a work colleague of mine ran into the very  
> same issue with R_AVR_13_PCREL and the tiny85. I was finally able to  
> track it down.
>
> Unfortunately it looks like a bona fide bug in binutils. I have a  
> patch, that so far seems to fix the problem. I just submitted the  
> patch upstream.
>
> Basically, the problem stems from the fact that the linker allows  
> all devices in only the avr2 and avr4 architectures to wrap around  
> the offsets. Devices in the avr25 architecture should be allowed to  
> do that too (as avr25 is the same as avr2, plus 2 extra  
> instructions), but for some reason it looks like the avr25 was  
> forgotten when it comes to this reloc. It just so happens that the  
> ATtiny85 belongs to the avr25 architecture. My work colleague  
> mentions that he doesn't have this problem when he uses an ATmega8  
> (with the same amount of code space). And that is because the  
> ATmega8 belongs to the avr4 architecture.
>
> I see you're using a Mac. The patch for binutils is attached.  
> Feedback on how it works for you would be appreciated. This fix will  
> be in the next WinAVR release.
>
> Eric Weddington
>
>
> <41-binutils-2.19-avr25-wraparound-reloc.patch>