Some Haifa scheduler bugs

[David Edelsohn]

>>>>> "David S Miller" writes:

Jeff> I'm less familiar with how this works under aix or with
Jeff> ultrasparcs/solaris, but I assume they both do something relatively
Jeff> reasonable.

David> Naturally, this depends upon OS support, and I think Solaris does map
David> page 0 in this special way, or they check the load instruction which
David> was executed by the user once the fault handling call chain determines
David> that the access was in outer space.

	The IBM XL compilers have a switch to disable the speculative load
optimization, but AIX does not have any way to make loads from page 0
generate a fault -- it is a general feature provided by the OS without
user control.  Neither the POWER/PowerPC architecture nor the executable
header have any selectable switch to enable or disable that general
functionality.

David