Messages in this thread | | | Date | Tue, 17 Dec 2002 11:54:01 -0800 | From | "H. Peter Anvin" <> | Subject | Re: Intel P6 vs P7 system call performance |
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Richard B. Johnson wrote: > > You can call intersegment with a full pointer. I don't know how > expensive that is. Since USER_CS is a fixed value in Linux, it > can be hard-coded > > .byte 0x9a > .dword 0xfffff000 > .word USER_CS > > No. I didn't try this, I'm just looking at the manual. I don't know > what the USER_CS is (didn't look in the kernel) The book says the > pointer is 16:32 which means that it's a dword, followed by a word. >
It's quite expensive (not as expensive as INT, but not that far from it), and you also push CS onto the stack.
-hpa
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