Thanks for reviewing this patch Balbir Balbir Singh <bsinghar...@gmail.com> writes:
> Any specific issue you've run into without this patch? Without this patch since xmon is still accessible via sysrq and there is no indication/warning on the xmon console mentioning that its is not fully functional. Specifically xmon-console would still allow user to set instruction/data breakpoint eventhough they wont work and will result in a kernel-oops. Below is command log illustrating this problem on one of my test system where I tried setting an instruction breakpoint on cmdline_proc_show() with xmon=off: ~# cat /proc/cmdline root=UUID=248ad10e-a272-4187-8672-5b25f701e8b9 ro xmon=off ~# echo 'x' > /proc/sysrq-trigger [ 458.904802] sysrq: SysRq : Entering xmon [ snip ] 78:mon> ls cmdline_proc_show cmdline_proc_show: c0000000004196e0 78:mon> bi c0000000004196e0 78:mon> x ~# cat /proc/cmdline [ 505.618702] Oops: Exception in kernel mode, sig: 5 [#1] [ snip ] [ 505.620082] NIP [c0000000004196e4] cmdline_proc_show+0x4/0x60 [ 505.620136] LR [c0000000003b1db0] seq_read+0x130/0x5e0 [ 505.620177] Call Trace: [ 505.620202] [c000200e5078fc00] [c0000000003b1d74] seq_read+0xf4/0x5e0 (unreliable) [ 505.620267] [c000200e5078fca0] [c00000000040cae0] proc_reg_read+0xb0/0x110 [ 505.620322] [c000200e5078fcf0] [c00000000037687c] __vfs_read+0x6c/0x1b0 [ 505.620376] [c000200e5078fd90] [c000000000376a7c] vfs_read+0xbc/0x1b0 [ 505.620430] [c000200e5078fde0] [c00000000037724c] SyS_read+0x6c/0x110 [ 505.620485] [c000200e5078fe30] [c00000000000b320] system_call+0x58/0x6c [ 505.620536] Instruction dump: [ 505.620570] 3c82ff2a 7fe3fb78 38a00000 3884dee0 4bf98c05 60000000 38210030 e8010010 [ 505.620656] ebe1fff8 7c0803a6 4e800020 3c4c00d6 <38422120> 7c0802a6 f8010010 f821ff91 [ 505.620728] ---[ end trace eaf583921860b3de ]--- [ 506.629019] Trace/breakpoint trap ~# > I presume running xmon=off indicates we don't want xmon to take over in case > of > panic/die/oops, I believe that when xmon console is available it should be fully functional rather than partially, otherwise it gets really confusing to the user as to why Instruction/Data break points arent working. > why are we tying this to sysrq? With xmon=off sysrq seems to be the only way to enter xmon console. -- Vaibhav Jain <vaib...@linux.vnet.ibm.com> Linux Technology Center, IBM India Pvt. Ltd.