On 10/01/2014 10:50 AM, H. Peter Anvin wrote: > On 09/30/2014 04:21 PM, Thomas Gleixner wrote: >>> >>> If we ever want those cycles back, I bet that the compat sysenter path >>> could be trimmed down a lot. For example, I think that all of the >>> zero-extension stuff is unnecessary now that we have the magic syscall >>> wrappers for all (?) syscalls. >> >> Emphasis on "(?)". So yes, once we verified that .... >> > > I don't think that's true. Many system calls use exactly the same entry > point for compat and noncompat calls. I don't see any value in > replicating that code in every system call. > > The only time we need to do anything horribly special is when we have an > argument which is a signed long, which fortunately is not at all common. >
Also, we still need to shuffle registers around to match the x86-64 calling convention. Zero extension as part of that shuffle is free. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/