Hi, Eric Weddington, Eric wrote: > You're right. That's exactly what we need.
FWIW, I think that is what the "used" attribute does. Specially with -combine -fwhole-program, gcc tends to throw away interrupt definitions if I don't precede them with __attribute__((used)), because apparently no one is calling them. This is not specific to AVR as I've seen it happen with ARM too, at least. >> -----Original Message----- >> From: Dale [mailto:d...@4drealtime.co.za] >> Sent: Thursday, November 01, 2012 9:05 AM >> To: Weddington, Eric >> Cc: brend...@computer.org; avr-libc-dev@nongnu.org >> 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: avr-libc-dev-bounces+eric.weddington=atmel....@nongnu.org >>>> [mailto:avr-libc-dev-bounces+eric.weddington=atmel....@nongnu.org] On >>>> Behalf Of Brendan Hanna >>>> Sent: Thursday, November 01, 2012 6:09 AM >>>> To: avr-libc-dev@nongnu.org >>>> 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. P.S.: please don't top-post... :( -- Paulo Marques Software Development Department - Grupo PIE, S.A. Phone: +351 252 290600, Fax: +351 252 290601 Web: www.grupopie.com "This version has many new and good features. Sadly, the good ones are not new and the new ones are not good." _______________________________________________ AVR-libc-dev mailing list AVR-libc-dev@nongnu.org https://lists.nongnu.org/mailman/listinfo/avr-libc-dev
