On Monday 16 May 2005 16:08, Young Koh wrote: > Hi, > > Could you explain what happens in SKAS mode, then? How a UML kenel in > SKAS mode handles the UML system calls differently from one in TT > mode? i tried to understand from the code, but i had hard time to > understand. The usage of PTRACE_SYSCALL is not very different in SKAS mode, the different thing is about the handling of child address spaces... however I'm going to publish some info on my site.
About the below, tracing in SKAS mode is simpler, because you don't switch tracing on and off. In TT mode, the tracing thread (which does not run kernel code, in fact in it current is invalid) ptraces the host threads, which run both the UML userspace code, and the UML kernelspace code (which runs in signal handlers). In SKAS mode, instead, the UML scheduler switches back and forth between various "processes" (inside UML) which are all running inside userspace, and ptrace the various host threads (actually collapsed into one userspace thread, thanks to SKAS mode) which run only the real userspace code. So the ptraced context always executes userspace code and we never turn ptracing off. -- Paolo Giarrusso, aka Blaisorblade Skype user "PaoloGiarrusso" Linux registered user n. 292729 http://www.user-mode-linux.org/~blaisorblade ------------------------------------------------------- This SF.Net email is sponsored by Oracle Space Sweepstakes Want to be the first software developer in space? Enter now for the Oracle Space Sweepstakes! http://ads.osdn.com/?ad_id=7412&alloc_id=16344&op=click _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
