this makes it possible to attach to linux process with linux gdb and
see top-most function on traceback; lower functions are not available,
probably due to bad frame setup
it's not possible to setup breakpoints - Linux gdb uses hw breakpoints,
so support for them would need to be written
Despite that /etc/amd.conf is now the default configuration file, it needs
to be defined if you supply other options when you start amd, so add it here.
- when pcb_onfault is set, allow UVM to attempt to resolve permission faults
as well as translation faults (rather than immediately invoking the
onfault handler for permission faults). this is needed for UBC since
it will be normal for uiomove() to fault on read-only mappings which
will be made writable by the pager.
- clear pcb_onfault before calling uvm_fault() and restore it afterward.
if the fault handler generates a pagefault, we'd like to panic rather
than invoking the onfault handler.
- allow entry of the same mapping that's already there.
this can happen with UBC.
- if PMAP_CANFAIL, return failure rather than sleeping
when we fail to allocate a ptp.
* move all exec-type specific information from struct emul to execsw[] and
provide single struct emul per emulation
* elf:
- kern/exec_elf32.c:probe_funcs[] is gone, execsw[] how has one entry
per emulation and contains pointer to respective probe function
- interp is allocated via MALLOC() rather than on stack
- elf_args structure is allocated via MALLOC() rather than malloc()
* ecoff: the per-emulation hooks moved from alpha and mips specific code
to OSF1 and Ultrix compat code as appropriate, execsw[] has one entry per
emulation supporting ecoff with appropriate probe function
* the makecmds/probe functions don't set emulation, pointer to emulation is
part of appropriate execsw[] entry
* constify couple of structures
as normal device interrupts. Because of this, we won't get IPIs while
servicing such interrupts. This can lead to the following deadlock
scenario as reported by Bill Sommerfeld:
- Process runs on cpu1, but has FP state on cpu0.
- Process executes FP-using insn, causing an FP trap, which causes
the kernel lock to be acquired.
- At roughly the same time, cpu0 receives a device interrupt, and attempts
to acquire the kernel lock, which blocks since cpu1 already has it.
- cpu1 sends cpu0 a SYNCH FPU IPI, and waits for cpu0 to release its
FP state.
- Since cpu0 cannot notice the IPI until it has processed the device
interrupt, which it cannot do because it cannot acquire the kernel
lock, we have deadlock.
Solve the problem by adding a spinlock interlock release hook which
checks for pending IPIs and processes them.
Idea from Bill Sommerfeld.
itojun