[PATCH] kdb on SMP (breakpoint hits multiple cpus simultaneously)

[Vamsi Krishna S .]

Yes, that is what I thought. My earlier patch fixed only the int3
points. I will do similar fix for debugreg breakpoints too
and update the man pages and code comments accordingly.

Thanks,
Vamsi.


On Thu, Apr 03, 2003 at 03:20:01PM +0800, Zhang, Sonic wrote:
> Hi,
> 
> 	Yes, the case you mentioned is possible in current KDB. I remember some related instructions in the KDB man pages. It is said that don't remove any break point when you enter KDB through DEBUG trap or Int3 trap, disable it instead and remove it safely later when you enter KDB via keyboard trap or serial port trap. 
> 
> 	Maybe your patch can clean up these comments in the man pages?
> 
> 	Regards.
> 
> 	Sonic Zhang
> 
> -----Original Message-----
> From: Vamsi Krishna S . [mailto:vamsi at in.ibm.com]
> Sent: 2003?4?3? 14:59
> To: Zhang, Sonic
> Cc: Keith Owens; Hua Qin; kdb at oss.sgi.com
> Subject: Re: [PATCH] kdb on SMP (breakpoint hits multiple cpus simultaneously)
> 
> 
> Hi,
> 
> Thanks for the clarification. I thought from my quick
> glance through that currently all hard breakpoints
> are global, whereas your patches enabled per-cpu
> breakpoints. On second look, you are right, the current
> code allows only per-cpu debugreg-breakpoints, global
> ones are much more generally useful, which your patch
> enables.
> 
> I also agree with the name changes and the fact that
> per-cpu breakpoints may be useful for debugging certain
> paths (processes) bound to a specific cpu.
> 
> smphdr* patches are very much needed.
> 
> Thanks,
> Vamsi.
> 
> BTW: Can you think about what happens if two debugreg
> breakpoints are triggered at about the same time on
> different cpus? One of them wins the race to enter
> the kdb, and then the user clears all breakpoints..
> will kdb be able still recognise this as one of its 
> breakpoints? I think not, but can you give it a thought?
> 
> -- 
> Vamsi Krishna S.
> Linux Technology Center,
> IBM Software Lab, Bangalore.
> Ph: +91 80 5044959
> Internet: vamsi at in.ibm.com

-- 
Vamsi Krishna S.
Linux Technology Center,
IBM Software Lab, Bangalore.
Ph: +91 80 5044959
Internet: vamsi at in.ibm.com