This change adds a TLB miss handler that calls __TLB_LoadPTEH() and
removes the startu mapping of add-in pages in the explore() routine of
src/core/start.c.
Note that calling __TLB_LoadPTEH() manually might unexpectedly lead to a
TLB multihit problem as the requested page might be accidentally loaded
by a TLB miss in the code that loads it. A TLB multihit is a platform
reset, so this function should always be considered unsafe to call
(unless the calling code is in a combination of P1 space and ILRAM).
This change also moves a lot of functions out of the .pretext section,
notably topti, as this was designed to allow panic messages when the
add-in couldn't be mapped entirely. By contrast, a GMAPPED macro has
been defined to mark crucial kernel code and data that must remain
mapped at all times. This currently puts the data in ILRAM because
static RAM is not executable. An alternative will have to be found for
SH3-based fx9860g machines.
This version still does not allow TLB misses in timer callbacks and
breaks return-to-menu in a severe way! It is not suitable for any
stable application!
This change modifies the fx-CG 50 linker script to allow add-ins up to
2M and no longer complains about add-ins that don't fit in the TLB.
It also exposes the __TLB_LoadPTEH() syscall (%003 on fx9860g, %00c on
fxcg50) that answers TLB misses. This syscall can be called manually
from an add-in to load some pages and seems to work without problem.
However, this version does not provide any automatic TLB management,
some key areas of the kernel are still under TLB and some user code
(such as timer callbacks) is not! This version is suitable only for
add-ins smaller than 220k!
Lephe