On Thu, 24 Apr 2008, David Miller wrote: > > 2) Make use of an unused field in pt_regs to store both > a magic number, and the trap number, this allows: > > a) Removing the funny passing of the "restart_syscall" > boolean in the trap return paths to the signal dispatch. > > b) Allow more accurate stack backtraces, since we have the > magic cookie, we can detect trap frames accurately. > > c) The UTRACE guys want to be able to detect if a thread > off the cpu is in a system call, they can do that trivially > now just like they can on x86. > > In fact much of this idea is from Roland McGrath. Heh. This is what x86 has done since day#1. I wonder why other architectures wouldn't have copied that part.. That's "orig_eax". It's a strange name, it really has nothing to do with "eax" except for the fact that the system call number comes from that register - for traps etc it's a negative value. Linus -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
