------- Comment #7 from torsten at debian dot org 2010-05-20 20:47 ------- This also hit me. I wanted to build a simple data logger for an ARM board. Of course I wanted to give gcc 4.4 a go (I used a compiler from the 3.x series before...), combined with current FreeRTOS (from www.freertos.org).
The interrupt handlers do not compile just as for Nut/OS. I found a discussion about the issue at the arm-gnu archives. Quoting the post at http://www.codesourcery.com/archives/arm-gnu/msg02517.html by Mark Mitchell: ----- This code makes invalid use of the "naked" attribute. >From the manual: "The only statements that can be safely included in naked functions are asm statements that do not have operands. All other statements, including declarations of local variables, if statements, and so forth, should be avoided. Naked functions should be used to implement the body of an assembly function, while allowing the compiler to construct the requisite function declaration for the assembler." ----- I disagree with this interpretation. "should" be avoided is different from "must". For me this is just an indication that nothing is guaranteed about the generated code - which is fine, interrupt handlers will naturally have to revised for compiler updates. Disregarding this as "invalid code" basically sends the signal that gcc is unusable for small embedded systems. Of course it is possible to create a trampoline function in assembler for each interrupt handler, but for small systems, the overhead is relevant. So I'd rather set up the required registers manually using some asm instructions but write the body of the function in C. Looking at FreeRTOS' Subversion repository, they already started to add an extra indirection to all interrupt handlers. :-( -- torsten at debian dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |torsten at debian dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43404
