On 9/24/08, David Miller <davem@xxxxxxxxxxxxx> wrote: > From: "Blue Swirl" <blauwirbel@xxxxxxxxx> > > Date: Wed, 24 Sep 2008 21:06:21 +0300 > > > > Now I found the relevant part in the manuals. The extra sun4v bit is > > not taken into account from user mode, so we can't catch privileged to > > hyperprivileged mode traps easily. > > > That's right, the top bit is ignored in user mode. The hypervisor uses traps 0x80, 0x83, 0x84, 0x85, and 0xff. Looking at how these alias to low number traps: first four are unused or used for resets (SIR, RED, XIR), so they are not in the fast path. 0xff aliases to 0x7f, which is part of Fill 7 otherwin trap. Maybe that is not performance critical? The Fill 7 trap entry could be shortened with off-table jumps. I'm thinking that we could disassemble the calling instruction on entry to the lower traps and detect what was the true cause of the trap. -- 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
