On Tue, Jun 30, 2020 at 04:02:31PM +0200, Peter Zijlstra wrote: > On Tue, Jun 30, 2020 at 03:55:05PM +0200, Rasmus Villemoes wrote: > > > > Consistently so with GCC-4.9. Any other GCC I tried does the sane thing. > > > > Does that include gcc 4.8, or is it only "anything newer than 4.9"? > > It includes 4.8 :-) > > > so the section it was put in has an alignment of 64. The generated > > assembly is indeed > > > > .globl fair_sched_class > > .section __fair_sched_class,"a",@progbits > > .align 64 > > > > /me goes brew coffee > > Right.. so I now have the below patch, and with that I get: > > 62931: c1e62c20 0 NOTYPE GLOBAL DEFAULT 2 __begin_sched_classes > 65736: c1e62e40 128 OBJECT GLOBAL DEFAULT 2 stop_sched_class > 71813: c1e62cc0 128 OBJECT GLOBAL DEFAULT 2 fair_sched_class > 78689: c1e62c40 128 OBJECT GLOBAL DEFAULT 2 idle_sched_class > 78953: c1e62ec0 0 NOTYPE GLOBAL DEFAULT 2 __end_sched_classes > 79090: c1e62d40 128 OBJECT GLOBAL DEFAULT 2 rt_sched_class > 79431: c1e62dc0 128 OBJECT GLOBAL DEFAULT 2 dl_sched_class > > > Which has me stumped on __begin_sched_classes being on a 32byte edge > (and crashes differently due to that).
OK, when I look at defconfig-build/arch/x86/kernel/vmlinux.lds I get: . = ALIGN(32); *(__dummy_sched_class) __begin_sched_classes = .; So I'm thinking the GCC_VERSION thing works for sched.h but not for arch//x86/kernel/vmlinux.lds.S, lovely. Let me try and figure out why.
