* Marc Zyngier <marc.zyngier@xxxxxxx> [121008 04:34]: > On 08/10/12 12:01, Dave Martin wrote: > > > > In an attempt to narrow this down... > > > > Can you follow this (i.e., _after_ a known successful switch to SVC mode) > > > > (a) > > mrs \reg, cpsr > > msr spsr_cxsf, \reg > > adr \reg, 3f > > movs pc, lr > > 3: > > > > and (b) > > > > mrs \reg, cpsr > > orr \reg, \reg, #CPSR_A_BIT > > msr cpsr_cxsf, \reg > > > > and (c) > > > > mrs \reg, cpsr > > orr \reg, \reg, #CPSR_A_BIT > > msr spsr_cxsf, \reg > > adr \reg, 3f > > movs pc, lr > > 3: > > > > > > > > > > If only (a) works, this would suggest that the attempt to set the A bit > > is causing the problem. > > > > If only (b) works, this suggests that the A bit is OK but that some > > invalid hardware state, or something else we don't understand, is causing > > exception returns to fail in general. > > > > If (a) and (b) work but (c) fails, this suggests that specifically > > trying to set the A bit via an exception return is problematic. > > > > If all of them work then this suggests some invalid hardware state or > > something else we don't understand, but which is cleared by the initial > > msr cpsr_c which clobbers the processor mode. Thanks it does not seem to be the A bit.. > Playing with an Integrator-CP with a 1136 tile, the only way I could > cause the thing to fail was to boot the thing in SYSTEM mode. > > Tony, can you possibly also try the attached patch? Yup you figured it out n800 is in system mode while 2430sdp is not.. I verified it with printhex2. Your patch fails to compile with: arch/arm/kernel/head.S: Assembler messages: arch/arm/kernel/head.S:336: Error: symbol `omgsys' is already defined Probably because it's included twice. Also, shouldn't it be bne omgsys instead of beq? Regards, Tony > diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h > index 683a1e6..7714ec7 100644 > --- a/arch/arm/include/asm/assembler.h > +++ b/arch/arm/include/asm/assembler.h > @@ -253,6 +253,8 @@ > mrs \reg , cpsr > mov lr , \reg > and lr , lr , #MODE_MASK > + cmp lr , #SYSTEM_MODE /* Yet another braindead platform? */ > + beq omgsys > cmp lr , #HYP_MODE > orr \reg , \reg , #PSR_A_BIT | PSR_I_BIT | PSR_F_BIT > bic \reg , \reg , #MODE_MASK > @@ -264,6 +266,7 @@ THUMB( orr \reg , \reg , #PSR_T_BIT ) > __MSR_ELR_HYP(14) > __ERET > 1: movs pc, lr > +omgsys: msr cpsr_c, \reg > 2: > .endm > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
