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On 03/21/16 02:11, Alex Bennée wrote: > > Peter Maydell <peter.mayd...@linaro.org> writes: > >> On 20 March 2016 at 19:20, Sean Bruno <sbr...@freebsd.org> >> wrote: >>> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 >>> >>> aarch64 targets are now failing to build on i386 hosts due to >>> missing __atomic_load_8() calls since this commit: >>> >>> https://github.com/qemu/qemu/commit/a0aa44b488b3601415d55041e4619aef5f3a4ba8#diff-c143d686899ae51d7b927d9c682e12fd >>> >>> >>> I'm unsure if Linux is disabling aarch64 targets for i386 hosts or if >>> this commit works "just fine" on Linux hosts right now, as it >>> doesn't work with clang or gcc. >> >> I think it just works on most Linux 32-bit architectures because >> the compiler support can inline a suitable atomic op (there is >> one case where it doesn't, which I think is PPC32). >> >> In any case, we mustn't use atomics on types larger than the host >> pointer type, because it's not portable enough. Paolo or Alex, >> can you have a look at this? > > I'll get a BSD up and running and check. What is triggering the > __atomic_load_8 though? > >> Specifically, its the atomic_read of vm_clock_warp_start in cpus.c: 114 /***********************************************************/ 115 /* guest cycle counter */ 116 117 /* Protected by TimersState seqlock */ 118 119 static bool icount_sleep = true; 120 static int64_t vm_clock_warp_start = -1; 121 /* Conversion factor from emulated instructions to virtual clock ticks. */ 122 static int icount_time_shift; .... 339 static void icount_warp_rt(void) 340 { 341 /* The icount_warp_timer is rescheduled soon after vm_clock_warp_start 342 * changes from -1 to another value, so the race here is okay. 343 */ 344 if (atomic_read(&vm_clock_warp_start) == -1) { 345 return; 346 } 347 -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQF8BAEBCgBmBQJW8Aq6XxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXRCQUFENDYzMkU3MTIxREU4RDIwOTk3REQx MjAxRUZDQTFFNzI3RTY0AAoJEBIB78oecn5kktIH+QHD8muIYbAPzJcBMIFv9zIR tv1OhxHgrWgmxnfzxeXwNkG5JkIrFKkJd6HoA4we+qrQu2Fi9ZCxz/cmFryNzXuT CQPGcEaKQvAVT9623UVtJkvKv1lFzpclX6wQKkAN1GtnoaoXmOntCoPQFR2/cha3 0YeLM/26nlKr6kcWbX5a5hplKnsPA7IY0lohWGp/qziZKuFQ7GWsM6IkyLoXRn+T T8Qw7NM40/iIvqYd7NfQlDlGa1GZo8mvsRvvF1C6YEkAmU9TkX0LfgGuIpiYmvYb gHEJ6JcXRQhGQXWkGu3Znw4JzckjfPrg0/SMIsk4kMVNXunJ89Il4xT8wtFXFYw= =Lehi -----END PGP SIGNATURE-----
