Hi Kevin, Stuart , Woohooo You guys spotted !. http://git.linux-mips.org/?p=linux.git;a=commit;h=d5ec6e3c seems to be the culprit Once I restored previous version of stackframe.h 2.6.33-stable started booting !. Thanks, Anoop On Fri, 2010-12-24 at 04:32 -0800, Kevin D. Kissell wrote: > Thank you, Stuart! I've spotted some definite breakage to SMTC between > those versions. In arch/mips/include/asm/stackframe.h, someone moved > the store of the Status register value in SAVE_SOME (line 169 or 204, > depending on the version) from two instructions after the mfc0 to a > point after the #ifdef for SMTC, presumably to get better pipelining of > the register access. Unfortunately, the v1 register is also used in the > SMTC-specific fragment to save TCStatus, so the Status value gets > clobbered before it gets stored. This will eventually result in the > Status register getting a TCStatus value, which has some bits on common, > but isn't identical and sooner or later Bad Things will happen. > > I'm a little surprised this wasn't caught by visual inspection of the patch. > > Possible solutions would include reverting the store of the CP0_STATUS > value to the block above the #ifdef, or, to retain whatever performance > advantage was obtained by moving the store downward, to use v0/$2 > instead of v1/$3, as the staging register for the TCStatus value. I'd > lean toward the second option, but I'm not in a position to test and > submit a patch just now. > > Regards, > > Kevin K. > > On 12/23/10 1:09 PM, STUART VENTERS wrote: > > Kevin, > > > > I'm not sure if it's useful, > > but finally I got the time to look at the two kernel versions Anoop pointed out. > > works 2.6.32-stable with patch 804 > > works_not 2.6.33-stable > > > > greping for files with CONFIG_MIPS_MT_SMTC > > and looking for timer interrupt related stuff found the following differences: > > > > > > arch/mips/include/asm/irq.h > > arch/mips/kernel/irq.c > > do_IRQ > > > > arch/mips/include/asm/stackframe.h > > SAVE_SOME SAVE_TEMP get/set_saved_sp > > > > arch/mips/include/asm/time.h > > clocksource_set_clock > > > > arch/mips/kernel/process.c > > cpu_idle > > > > arch/mips/kernel/smtc.c > > __irq_entry > > ipi_decode > > SMTC_CLOCK_TICK > > > > > > Enclosed are the two subsets of files for a more expert look. > > > > I'll try to look in more detail after Christmas. > > > > > > Cheers, > > > > Stuart > > > > > > > > >
