> I had a surprise when I tried to debug a user process on the > raspberry pi. The first time it hit a breakpoint, the kernel > panicked. Oops. > > It turns out than on armv6 (and armv7, I think) the breakpoint > instruction causes a Prefetch Abort exception, instead of Undefined > Instruction as on previous arm architectures. > > I've updated the rpi kernel source to deal with this. I wonder if > somebody with plan 9 on an armv7 system (omap or teg2) could check > whether the same panic occurs there too?
I just played a bit with acid on my IGEPv2 (omap) and Trim-Slice (teg2), and I experienced the same problem with both. cpu% acid /bin/ls /bin/ls:arm plan 9 executable /sys/lib/acid/port /sys/lib/acid/arm acid: new() Then acid hangs forever. When I interrupt it: 135: SVC/SWI Exception _main MOVW.W R14,#-0x54(R13) <stdin>:2: (error) msg: pid=135 startstop: interrupted acid: Acid on acid: cpu% acid 209 /proc/209/text:arm plan 9 executable /sys/lib/acid/port /sys/lib/acid/arm acid: stk() pwrite()+0xc /sys/src/libc/9syscall/pwrite.s:6 write(buf=0x3dd4d,n=0x9)+0x1c /sys/src/libc/9sys/write.c:7 msg(msg=0x3dd4d,pid=0xd2)+0x58 /sys/src/cmd/acid/proc.c:231 startstop(args=0xaf300)+0x78 /sys/src/cmd/acid/builtin.c:238 ocall(res=0x1fffd368,n=0xaf360)+0x88 /sys/src/cmd/acid/expr.c:963 execute(n=0xaf360)+0x30c /sys/src/cmd/acid/exec.c:94 execute(n=0xaf3c0)+0x14c /sys/src/cmd/acid/exec.c:123 call(parameters=0x0,fn=0xae580,local=0x0,retexp=0x1fffe520,body=0xaf3c0)+0x2ac /sys/src/cmd/acid/exec.c:490 ocall(res=0x1fffe520,n=0xb75a0)+0xec /sys/src/cmd/acid/expr.c:970 execute(n=0xb75a0)+0x30c /sys/src/cmd/acid/exec.c:94 execute(n=0xb7600)+0x14c /sys/src/cmd/acid/exec.c:123 execute(n=0xb77e0)+0x140 /sys/src/cmd/acid/exec.c:122 call(parameters=0x0,fn=0xb6e90,local=0x0,retexp=0x1ffff76c,body=0xb77e0)+0x2ac /sys/src/cmd/acid/exec.c:490 ocall(res=0x1ffff76c,n=0xf94a8)+0xec /sys/src/cmd/acid/expr.c:970 execute(n=0xf94a8)+0x30c /sys/src/cmd/acid/exec.c:94 yyparse()+0xefc /sys/src/cmd/acid/dbg.y:55 main(argv=0x1fffffb0,argc=0x1)+0x2ac /sys/src/cmd/acid/main.c:150 _main+0x28 /sys/src/libc/arm/main9.s:19 acid: On the Trim-Slice, the kernel write the following message in the console: trap: cpu1: i-fault va 0x1024 != ifar 0x1020 -- David du Colombier
