Am 06.05.2012 13:32, schrieb Blue Swirl: > On Sat, May 5, 2012 at 3:37 PM, Andreas Färber <afaer...@suse.de> wrote: >> Hello Blue, >> >> Testing a potential AREG0 fix for ppc host by malc I got an error >> running `./sparc-softmmu/sparc-softmmu` (same with CD/kernel): >> >> qemu: fatal: Trap 0x07 while interrupts disabled, Error state >> pc: 00005e0c npc: 00005e10 >> General Registers: >> %g0-7: 00000000 00000001 babababa 00000000 00000020 07ffff08 07ffe000 >> babababa >> >> Current Register Window: >> %o0-7: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >> 00000000 >> %l0-7: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >> 00000000 >> %i0-7: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 >> 00000000 >> >> Floating Point Registers: >> %f00: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> %f08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> %f16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> %f24: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> psr: 048000c0 (icc: N--- SPE: SP-) wim: 00000001 >> fsr: 00000000 y: 00000020 >> Abgebrochen >> >> The 0xbabababa in %g2 and %g7 is a signature I've seen in uninitialized >> memory on openSUSE 12.1 Betas. So I ran valgrind, and the following >> caught my eye on both ppc and x86_64: >> >> ==18801== Command: ./sparc-softmmu/qemu-system-sparc >> ==18801== >> ==18801== Thread 2: >> ==18801== Conditional jump or move depends on uninitialised value(s) >> ==18801== at 0x25C5AF: compute_all_logic (cc_helper.c:37) >> ==18801== by 0x25C648: helper_compute_psr (cc_helper.c:470) >> ==18801== by 0x8CD0981: ??? >> ==18801== Uninitialised value was created by a heap allocation >> ==18801== at 0x4C27CE8: memalign (in >> /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) >> ==18801== by 0x4C27D97: posix_memalign (in >> /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) >> ==18801== by 0x1F2101: qemu_memalign (oslib-posix.c:93) >> ==18801== by 0x1F21A9: qemu_vmalloc (oslib-posix.c:126) >> ==18801== by 0x2665F6: qemu_ram_alloc_from_ptr (exec.c:2647) >> ==18801== by 0x286D76: memory_region_init_ram (memory.c:954) >> ==18801== by 0x297FFD: ram_init1 (sun4m.c:757) >> ==18801== by 0x204DAE: qdev_init (qdev.c:151) >> ==18801== by 0x204EEC: qdev_init_nofail (qdev.c:258) >> ==18801== by 0x298845: ram_init.constprop.7 (sun4m.c:783) >> ==18801== by 0x298980: sun4m_hw_init (sun4m.c:862) >> ==18801== by 0x2994A2: ss5_init (sun4m.c:1289) >> >> This is at 8f473dd104f0937ce98523fa6f9de0bd845aebbe, and cc_helper.c:37 >> is int32_t dst argument of get_NZ_icc(), which is always called with >> CC_DST, i.e. env->cc_dst. >> >> This seems to indicate that a read from uninitialized memory occurred, >> from which cc_dst is being initialized? > > This should happen in target-sparc/cpu.c:45 > memset(env, 0, offsetof(CPUSPARCState, breakpoints)); > > cc_dst is between structure start and CPU_COMMON. > > 89aaf60dedbe0e6415acfe816e02b538e5c54e68 fixed a bug relating to reset > recently.
The still-current master commit above includes that fix though, and that's no explanation for the uninitialized memory stemming from sun4m RAM as opposed to QOM object_new(). Somewhere a read is happening, possibly in OpenBIOS, from uninitialized memory that is then stored into the CPUSPARCState after that has been zero-initialized, IIUC. My issue here is that sparc64 boots HelenOS fine up until it's trying to load the kernel (identical to x86_64 host) but sparc32 exits really early on ppc. It might well be that there's a bug hidden in malc's TCG patch that's causing the fatal error state, but the uninitialized memory report is on both TCG hosts, so unlikely TCG-related. /-F >> Any idea where that could originate from or how to further debug? >> It doesn't seem to be caused by the >> 7d21dcc84b8c07918124a9c0708694d2fb013f65 OpenBIOS r1056 update. >> >> Regards, >> >> Andreas -- SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
