I dug into this some more, and it looks like it really is because the memory system doesn't enforce locking a particular address. Specifically here:
5049193421500: system.cpu0 T0 : @_spin_lock_irqsave+3.1 : DEC_LOCKED_M : ldstl t1d, DS:[rdi] : MemRead : D=0x0000000000000000 A=0xffffffff80768400 5049193435000: system.cpu1 T0 : @generic_unplug_device+24.0 : MOV_R_M : ld rax, DS:[rbx + 0x180] : MemRead : D=0xffffffff80768400 A=0xffff8100075f62c8 5049193436000: system.cpu1 T0 : @generic_unplug_device+31.0 : MOV_M_I : limm t1d, 0x1 : IntAlu : D=0x0000000000000001 5049193421500: system.cpu0 T0 : @_spin_lock_irqsave+3.2 : DEC_LOCKED_M : subi t1d, t1d, 0x1 : IntAlu : D=0x0000000000000094 5049193421500: system.cpu0 T0 : @_spin_lock_irqsave+3.3 : DEC_LOCKED_M : stul t1d, DS:[rdi] : MemWrite : D=0x00000000ffffffff A=0xffffffff80768400 5049193436000: system.cpu1 T0 : @generic_unplug_device+31.1 : MOV_M_I : st t1d, DS:[rax] : MemWrite : D=0x0000000000000001 A=0xffffffff80768400 You can more or less see where accesses to a spin lock are getting jumbled and the spin lock getting set to -1 because one CPU is clobbering the other's store. Shortly after that point, CPU 1 seems to go to sleep, and CPU 0 spins forever waiting for that -1 to become a 0. \/\/\/\/ So if any of you memory system folks are reading this, the memory system not respecting the lock request flags is a fairly serious problem that really deserves some attention. /\/\/\/\ Gabe On 02/26/12 04:51, Gabe Black wrote: > I looked into this more, and the code that sets up the memory hierarchy > was broken a little while ago. I have a patch that seems to fix it > (attached) but then it gets stuck a little later. I remember a while ago > someone had problems with atomic operations not being supported by the > memory system fully, but I don't remember the specifics. This might be > that problem too. > > Gabe > > On 02/24/12 02:45, Gabriel Michael Black wrote: >> Yes, I have. You're using O3 though, and that support is fairly new. >> >> Gabe >> >> Quoting "Ankita (Garg) Goel" <[email protected]>: >> >>> Hi, >>> >>> Has anyone been able to boot multiple cpus wth FS mode on x86 ? If >>> yes, it >>> would greatly help if you could share your environmental setup. The >>> issues >>> I am facing I have already posted in some previous emails. >>> >>> Thanks for your help! >>> >>> -- >>> Regards, >>> Ankita >>> >> >> >> _______________________________________________ >> gem5-users mailing list >> [email protected] >> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users > > > _______________________________________________ > gem5-users mailing list > [email protected] > http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
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