Date: Fri, 7 Aug 2020 12:46:00 +0200 From: Szabolcs Nagy <nsz@...t70.net> To: "Gamble, Bradley" <bradley.gamble@...pher.com> Cc: "musl@...ts.openwall.com" <musl@...ts.openwall.com> Subject: Re: Support for PowerPC64 devices lacking AltiVec extentions * Gamble, Bradley <bradley.gamble@...pher.com> [2020-08-07 10:15:38 +0000]: > I was initially encountering exceptions with longjmp()/setjmp() due to the use of lvx/stvx instructions to store and restore vector registers. These vector registers are AltiVec-specific and are not required for devices that do not have the AltiVec extentions, so simply removing them was enough to allow musl to function properly on e5500 devices. > > I initially considered whether a compile-time check in the configure script was possible, however I believe this has to be a run-time check to query whether the processor supports AltiVec extentions and to conditionally store/restore the registers if it does. I see that Arm targets use __hwcap for platform-specific functionality, and in hwcap.h for PowerPC64 there is a "PPC_FEATURE_HAS_ALTIVEC" definition. > > Would this be the correct way to detect this platform-specific behavior? __hwcap is the right check (e.g. used in the arm setjmp) it works if the missing altivec does not affect the call abi of standard c functions (otherwise fixing setjmp/longjmp alone will not help: a separate build of libc is needed targetting your system's call abi).
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.