Re: [avr-libc-dev] Possible hole in the assembler interrupt documentation

[Weddington, Eric]

You're right. That's exactly what we need.

Eric

> -----Original Message-----
> From: Dale [mailto:address@hidden
> Sent: Thursday, November 01, 2012 9:05 AM
> To: Weddington, Eric
> Cc: address@hidden; address@hidden
> Subject: Re: [avr-libc-dev] Possible hole in the assembler interrupt
> documentation
> 
> Hi,
> 
> Its not just an assembler issue, I've been bitten by this with 'C' code
> as well. If the ISR is the only code compiled into an object module, ie.
> with no references to code or variables in other object modules, it
> won't be linked into the app.
> 
> It would be useful if there was an attribute on all ISR declarations
> which indicate to the linker that they are to be kept regardless of
> whether they are referenced by other code.
> 
> > Hi Brendan,
> >
> > Thanks for pointing this out. Admittedly, there are not a lot of people
> who write their ISR in assembly. Most are able to write their ISRs in C.
> >
> > Would you be willing to fill out a bug report on the avr-libc project?
> Emails have a tendency to be forgotten about over time and we want to make
> sure that we capture this issue in our system so we can get the
> documentation fixed.
> >
> > Thanks,
> > Eric Weddington
> >
> > > -----Original Message-----
> > > From: address@hidden
> > > [mailto:address@hidden On
> > > Behalf Of Brendan Hanna
> > > Sent: Thursday, November 01, 2012 6:09 AM
> > > To: address@hidden
> > > Subject: [avr-libc-dev] Possible hole in the assembler interrupt
> > > documentation
> > >
> > > Hello,
> > >
> > > I have just spent some time trying to get my freshly minted interrupt
> > > vector to linked into my executable and appear in the vector table at
> the
> > > start of flash. I feel that there is a small, but non-obvious hole in
> the
> > > interrupt documentation that could be patched up.
> > >
> > > I had written my ISR in assembler but for the life of me could not
> figure
> > > why it had not been linked into the main application. I thought the
> 1.6.4
> > > libc documentation was implying that all I needed to do was name the
> vector
> > > with one of the standard vector names (PCINT0_vect in my case), and
> like
> > > magic all the pieces would come together.
> > >
> > > It took me some time to realise that the vector would not be considered
> for
> > > linking unless its object file contained a dependency required by the
> main
> > > object file. In real life this would probably be achieved with some ISR
> > > initialisation code defined in the assembly source file and called at
> start
> > > up. My organically growing code did not have this yet - so I had to
> falsify
> > > it with a global variable accessed by the main application but defined
> in
> > > assembly.
> > >
> > > I thought raising this issue here could help improve the documentation
> a
> > > little.
> > >
> > > Thanks,
> > >
> > > bOfWagg
> > >
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