[Python-Dev] Issue #8863 adds a new?PYTHONNOFAULTHANDLER?environment variable (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Thu Dec 23 19:57:21 CET 2010

Horrible or not, the existence of attribute(signal) seems to indicate that this is the case on some platform, or at least was historically.

The signal attribute has an effect only on ATMEL AVR processors, according to the documentation (and according to my source grep). On other processors, gcc typically implements attribute((interrupt)), meaning that the function is an interrupt handler - something that you cannot express in regular C. This may involve re-enabling interrupts on entry, but may also involve other code generation aspects (such as using iret instead of ret on x86).

For AVR, there was apparently some compatibility issue, introducing the need for two different ways to declare an ISR: attribute((interrupt)) causes interrupts to be re-enabled on entry (using the "sei" instruction); attribute((signal)) keeps them disabled.

So this has nothing to do with Unix signals.

Regards, Martin

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