tech-kern archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Trampolines on x86


Lars and me encountered a number of problems with iret and trampolines
on x86. Therefor, we wondered of what use trampolines still are on
x86 (i386 and amd64) are these days. Considering the fact that we're
using lazy mapping tricks, wouldn't the trampoline be more of a
performance drain than the gain it originally intented?

In order to solve the bug we're currently tracing, we would need to
add special handling code to the iret operation which would make the
regular trampoline code slower. In order to avoid hitting this in
future NetBSD releases, we'd like to disable trampolines entirely.
Compat code however would retain them (obviously) and run slower.

Are there any thoughts or objections on this?


Attachment: pgpRy231hj3Mj.pgp
Description: PGP signature

Home | Main Index | Thread Index | Old Index