I see you are kind of copying the file structure of ARM. I'm not sure this is a good example for a simple port. m68k is more straightforward.
-Gedare On Fri, Jul 18, 2014 at 10:17 AM, Gedare Bloom <ged...@rtems.org> wrote: > On Fri, Jul 18, 2014 at 1:35 AM, Hesham Moustafa > <heshamelmat...@gmail.com> wrote: >> >> On Thu, Jul 17, 2014 at 3:10 PM, Joel Sherrill >> <joel.sherr...@oarcorp.com> wrote: >> > This definitely sounds like not handling the context switch necessary >> > part of the >> > IRQ processing properly so always returning to IDLE. I call this a >> > simple return. >> > >> > All ports have a version of this code. no_cpu should have reasonable >> > pseudo-code. >> > m68k is likely the easiest to read as real code. >> > >> > You need to do a simple return if: >> > >> > (a) IRQ is nested, or >> > (b) DISPATCH_NEEDED is false >> > >> This is a macro that defines the address of the corresponding variable >> within the per cpu config table right? Please correct the following if >> I it's wrong. From assembly (when doing restore after C ISR handler is >> executed), I have to load this variable value, check if it's true >> (greater than zero), and if yes, jump to _ISR_Dispatch. I am a little >> confused what context should be loaded in both cases of: simple >> return, and _ISR_Dispatch; In case of _ISR_Dispatch, should I save >> stack pointer and return address and other context like normal context >> switch (function call)? While in interrupt context (simple return), I >> am saving almost all registers with some other necessary registers >> related to exceptions. >> > Please see > http://rtems.org/onlinedocs/doc-current/share/rtems/html/porting/Interrupts-Interrupt-Dispatching.html#Interrupts-Interrupt-Dispatching > > Summarizing: > > You need to update a few variables before calling the user ISR: > _Thread_Dispatch_disable_level += 1 > _ISR_Nest_level += 1 > > And decrement them after returning. > If ISRs are nested you do a simple return. > > Then you need to check if _CPU_ISR_Dispatch_disable is set, if so do a > simple return. > > Then you need to check if DISPATCH_NEEDED, if so you need to do the > ISR_Dispatch. > > >> One thing I have a problem with, is when using some macros like >> DISPATCH_NEEDED (it's a variable address right?) I am normally >> including rtems/score/percpu.h from the assembly file (which does the >> magic) to get these definitions but the compiler suffers. I think I >> have to provide compiler option or something to just include #define >> macros? If yes, where to add it? >> > Make sure to include rtems/asm.h before including percpu.h so you get > the ASM defines instead of C defines, since you are (presumably) > writing this in assembly. You could also use inline assembly, but then > you need to use expression operands [1] to provide access to these > variables instead. > > [1] https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html > > -Gedare > >> > Otherwise, you need to some CPU specific magic to get our of the IRQ and >> > back to the thread. Make it look like it called _Thread_Dispatch with >> > sufficient saved registers (e.g. callee destroyed). This is usually called >> > _ISR_Dispatch. When the call from _ISR_Dispatch to _Thread_Dispatch >> > returns, you do the magic needed to return tot he interrupted thread >> > (IDLE in this case) as if nothing happened. _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
