On Tuesday 01 October 2013 12:01 PM, Michael Ellerman wrote: > Hi Maddy, > > On Fri, Sep 27, 2013 at 05:03:54PM +0530, Madhavan Srinivasan wrote: >> powerpc/kernel/sysfs.c exports purr with write permission. > > PURR > >> This is only valid for kernel in hypervisor mode. >> But writing to the file in PowerVM lpar causes crash. > > In the kernel history/source we refer to it as "phyp". However in this
Will follow the convention. > case it's not an issue with phyp, it's simply that you are not in > hypervisor mode, ie. the same crash would occur under KVM. > > So you should just say "writing to the file in guest mode .." > Sure. Will make the changes. >> # echo 0 > purr >> cpu 0x0: Vector: 700 (Program Check) at [c000000000d072b0] >> pc: c00000000001770c: .write_purr+0x1c/0x40 >> lr: c000000000017708: .write_purr+0x18/0x40 >> sp: c000000000d07530 >> msr: 8000000000049032 >> current = 0xc000000000c53de0 >> paca = 0xc00000000ec70000 softe: 0 irq_happened: 0x01 >> pid = 0, comm = swapper/0 >> enter ? for help >> [c000000000d075b0] c0000000000fba64 >> .generic_smp_call_function_single_interrupt+0x104/0x190 >> [c000000000d07650] c000000000037748 .smp_ipi_demux+0xa8/0xf0 >> [c000000000d076e0] c000000000035314 .doorbell_exception+0x74/0xb0 >> [c000000000d07760] c000000000002950 doorbell_super_common+0x150/0x180 >> --- Exception: a01 (Doorbell) at c000000000060904 >> .plpar_hcall_norets+0x84/0xd4 >> [link register ] c00000000006dbd4 .check_and_cede_processor+0x24/0x40 >> [c000000000d07a50] c000000001002558 (unreliable) >> [c000000000d07ac0] c00000000006dd0c .shared_cede_loop+0x2c/0x70 >> [c000000000d07b40] c0000000006ae954 .cpuidle_enter_state+0x64/0x150 >> [c000000000d07c00] c0000000006aeb30 .cpuidle_idle_call+0xf0/0x300 >> [c000000000d07cb0] c000000000062fa0 .pseries_lpar_idle+0x10/0x50 >> [c000000000d07d20] c000000000016d14 .arch_cpu_idle+0x64/0x150 >> [c000000000d07da0] c0000000000e0060 .cpu_startup_entry+0x1a0/0x2c0 >> [c000000000d07e80] c00000000000bca4 .rest_init+0x94/0xb0 >> [c000000000d07ef0] c000000000b54530 .start_kernel+0x478/0x494 >> [c000000000d07f90] c000000000009be0 .start_here_common+0x20/0x40 >> 0:mon> >> >> Changes: >> >> 1)Changed the test for to hypervisor mode instead of platform > > I think Ben's wrong about that. > > Almost all existing code uses FW_FEATURE_LPAR to differentiate > hypervisor vs guest mode, so I think we should do the same here. > > So it would be: > >> + if (cpu_has_feature(CPU_FTR_PURR)) { >> + if (!firmware_has_feature(FW_FEATURE_LPAR)) >> + add_write_permission_dev_attr((void *)&dev_attr_purr); >> device_create_file(s, &dev_attr_purr); >> + } > Will modify the check. > >> +static void add_write_permission_dev_attr(void *ptr) >> +{ >> + struct device_attribute *attr = (struct device_attribute *)ptr; >> + >> + attr->attr.mode |= (unsigned short) 0200; >> +} > > Why does it take a void *, which then requires a cast at the call site? > just prefered to send the address as void. > And do you need the cast to short? If so shouldn't you use umode_t > directly? No, not really. Will make the changes and will resend the patch. > > cheers > Thanks for feedback. Maddy _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev