with the COMPAT_LINUX32 option. This is largely based on the i386 MD Linux
emulations bits, but also builds on the 32-bit FreeBSD and generic IA-32
binary emulation work.
Some of this is still a little rough around the edges, and will need to be
revisited before 32-bit and 64-bit Linux emulation support can coexist in
the same kernel.
logical CPUs on a system to be used as a dedicated watchdog to cause a
drop to the debugger and/or generate an NMI to the boot processor if
the kernel ceases to respond. A sysctl enables the watchdog running
out of the processor's idle thread; a callout is launched to reset a
timer in the watchdog. If the callout fails to reset the timer for ten
seconds, the watchdog will fire. The sysctl allows you to select which
CPU will run the watchdog.
A sample "debug.leak_schedlock" is included, which causes a sysctl to
spin holding sched_lock in order to trigger the watchdog. On my Xeons,
the watchdog is able to detect this failure mode and break into the
debugger, which cannot otherwise be done without an NMI button.
This option does not currently work with sched_ule due to ule's push
notion of scheduling, similar to machdep.hlt_logical_cpus failing to
work with that scheduler.
On face value, this might seem somewhat inefficient, but there are a
lot of dual-processor Xeons with HTT around, so using one as a watchdog
for testing is not as inefficient as one might fear.
to allow dumping per-thread machine specific notes. On ia64 we use this
function to flush the dirty registers onto the backingstore before we
write out the PRSTATUS notes.
Tested on: alpha, amd64, i386, ia64 & sparc64
Not tested on: arm, powerpc
are resevered, they can be written with anything, but they always read
as zero, we should simulate it in set_regs() as we are reading/writting
real hardware %rflags register.
becauses some syscalls using set_mcontext can sneakily change
parameters and later when those syscalls references parameters,
they will wrongly use register values in mcontext_t.
Approved by: peter
vm_page_sleep_if_busy() and the page table page's busy flag as a
synchronization mechanism on page table pages.
Also, relocate the inline pmap_unwire_pte_hold() so that it can be used
to shorten _pmap_unwire_pte_hold() on alpha and amd64. This places
pmap_unwire_pte_hold() next to a comment that more accurately describes
it than _pmap_unwire_pte_hold().
being defined, define and use a new MD macro, cpu_spinwait(). It only
expands to something on i386 and amd64, so the compiled code should be
identical.
Name of the macro found by: jhb
Reviewed by: jhb
their own directory and module, leaving the MD parts in the MD
area (the MD parts _are_ part of the modules). /dev/mem and /dev/io
are now loadable modules, thus taking us one step further towards
a kernel created entirely out of modules. Of course, there is nothing
preventing the kernel from having these statically compiled.
- Enable recursion on the page queues lock. This allows calls to
vm_page_alloc(VM_ALLOC_NORMAL) and UMA's obj_alloc() with the page
queues lock held. Such calls are made to allocate page table pages
and pv entries.
- The previous change enables a partial reversion of vm/vm_page.c
revision 1.216, i.e., the call to vm_page_alloc() by vm_page_cowfault()
now specifies VM_ALLOC_NORMAL rather than VM_ALLOC_INTERRUPT.
- Add partial locking to pmap_copy(). (As a side-effect, pmap_copy()
should now be faster on i386 SMP because it no longer generates IPIs
for TLB shootdown on the other processors.)
- Complete the locking of pmap_enter() and pmap_enter_quick(). (As of now,
all changes to a user-level pmap on alpha, amd64, and i386 are performed
with appropriate locking.)
dereference curthread. It is called only from critical_{enter,exit}(),
which already dereferences curthread. This doesn't seem to affect SMP
performance in my benchmarks, but improves MySQL transaction throughput
by about 1% on UP on my Xeon.
Head nodding: jhb, bmilekic
the thread ID and call db_trace_thread().
Since arm has all the logic in db_stack_trace_cmd(), rename the
new DB_COMMAND function to db_stack_trace to avoid conflicts on
arm.
While here, have db_stack_trace parse its own arguments so that
we can use a more natural radix for IDs. If the ID is not a thread
ID, or more precisely when no thread exists with the ID, try if
there's a process with that ID and return the first thread in it.
This makes it easier to print stack traces from the ps output.
requested by: rwatson@
tested on: amd64, i386, ia64
a fast interrupt handler doing an swi_sched(). This fixed the lockups I
saw on my laptop when using xmms in KDE and on rwatson's MySQL benchmarks
on SMP. This will eventually be removed and/or modified when I figure out
what the root cause is and fix that.
NO_ADAPTIVE_MUTEXES. This option has been enabled by default on amd64 for
quite some time, and has been extensively tested on i386 and sparc64. It
shows measurable performance gains in many circumstances, and few negative
effects. It would be nice in t he future if adaptive mutexes actually went
to sleep after a certain amount of spinning, but that will require quite a
bit more testing.
pmap_protect() and pmap_remove(). In general, they require the lock in
order to modify a page's pv list or flags. In some cases, however,
pmap_protect() can avoid acquiring the lock.
reduces the size of the pv_entry structure a small but significant amount.
This is implemented a little differently because it isn't so cheap to get
the physical address of the page tabke page on amd64.. instead of it
being directly accessible from the top level page directory, it is now
two additional tree levels down. However.. In almost all cases, we
recently had the physical address if the page table page a short while
before we needed it, but it slipped through our fingers. This patch
saves it for when we do need it. Also, for the one case where we do not
have the ptp paddr, we are always running in curproc context and so we
can do a vtopte-like trick. I've implemented vtopde() for this purpose.
There is still a CYA entry in pmap_unuse_pt() that needs to be removed. I
think it can be removed now but I forgot to test with it gone.
pmap_remove_pages(). (The implementation of pmap_remove_pages() is
optional. If pmap_remove_pages() is unimplemented, the acquisition and
release of the page queues lock is unnecessary.)
Remove spl calls from the alpha, arm, and ia64 pmap_remove_pages().
This also fixes the (runtime) breakage introduced in the previous
commit that was the result of a botched merge. This hasn't even
been compile-tested...
Most of the changes are a direct result of adding thread awareness.
Typically, DDB_REGS is gone. All registers are taken from the
trapframe and backtraces use the PCB based contexts. DDB_REGS was
defined to be a trapframe on all platforms anyway.
Thread awareness introduces the following new commands:
thread X switch to thread X (where X is the TID),
show threads list all threads.
The backtrace code has been made more flexible so that one can
create backtraces for any thread by giving the thread ID as an
argument to trace.
With this change, ia64 has support for breakpoints.
o Make debugging support conditional upon KDB instead of DDB.
o Remove implementation of Debugger().
o Don't make setjump() and longjump() conditional upon DDB.
o s/ddb_on_nmi/kdb_on_nmi/g
o Call kdb_reenter() when kdb_active is non-zero. Call kdb_trap()
otherwise.
a PCB from a trapframe for purposes of unwinding the stack. The PCB
is used as the thread context and all but the thread that entered the
debugger has a valid PCB.
This function can also be used to create a context for the threads
running on the CPUs that have been stopped when the debugger got
entered. This however is not done at the time of this commit.
in which multiple (presumably different) debugger backends can be
configured and which provides basic services to those backends.
Besides providing services to backends, it also serves as the single
point of contact for any and all code that wants to make use of the
debugger functions, such as entering the debugger or handling of the
alternate break sequence. For this purpose, the frontend has been
made non-optional.
All debugger requests are forwarded or handed over to the current
backend, if applicable. Selection of the current backend is done by
the debug.kdb.current sysctl. A list of configured backends can be
obtained with the debug.kdb.available sysctl. One can enter the
debugger by writing to the debug.kdb.enter sysctl.
backend improves over the old GDB support in the following ways:
o Unified implementation with minimal MD code.
o A simple interface for devices to register themselves as debug
ports, ala consoles.
o Compression by using run-length encoding.
o Implements GDB threading support.
bootp -> BOOTP
bootp.nfsroot -> BOOTP_NFSROOT
bootp.nfsv3 -> BOOTP_NFSV3
bootp.compat -> BOOTP_COMPAT
bootp.wired_to -> BOOTP_WIRED_TO
- i.e. back out the previous commit. It's already possible to
pxeboot(8) with a GENERIC kernel.
Pointed out by: dwmalone
BOOTP -> bootp
BOOTP_NFSROOT -> bootp.nfsroot
BOOTP_NFSV3 -> bootp.nfsv3
BOOTP_COMPAT -> bootp.compat
BOOTP_WIRED_TO -> bootp.wired_to
This lets you PXE boot with a GENERIC kernel by putting this sort of thing
in loader.conf:
bootp="YES"
bootp.nfsroot="YES"
bootp.nfsv3="YES"
bootp.wired_to="bge1"
or even setting the variables manually from the OK prompt.
than as one-off hacks in various other parts of the kernel:
- Add a function maybe_preempt() that is called from sched_add() to
determine if a thread about to be added to a run queue should be
preempted to directly. If it is not safe to preempt or if the new
thread does not have a high enough priority, then the function returns
false and sched_add() adds the thread to the run queue. If the thread
should be preempted to but the current thread is in a nested critical
section, then the flag TDF_OWEPREEMPT is set and the thread is added
to the run queue. Otherwise, mi_switch() is called immediately and the
thread is never added to the run queue since it is switch to directly.
When exiting an outermost critical section, if TDF_OWEPREEMPT is set,
then clear it and call mi_switch() to perform the deferred preemption.
- Remove explicit preemption from ithread_schedule() as calling
setrunqueue() now does all the correct work. This also removes the
do_switch argument from ithread_schedule().
- Do not use the manual preemption code in mtx_unlock if the architecture
supports native preemption.
- Don't call mi_switch() in a loop during shutdown to give ithreads a
chance to run if the architecture supports native preemption since
the ithreads will just preempt DELAY().
- Don't call mi_switch() from the page zeroing idle thread for
architectures that support native preemption as it is unnecessary.
- Native preemption is enabled on the same archs that supported ithread
preemption, namely alpha, i386, and amd64.
This change should largely be a NOP for the default case as committed
except that we will do fewer context switches in a few cases and will
avoid the run queues completely when preempting.
Approved by: scottl (with his re@ hat)
wasn't actually clean, it was saving the xmm registers as left over by the
bios. fninit() doesn't clear those.
In fpudna(), instead of doing a fninit() and forgetting to load the initial
mxcsr, do a full fxrstor(&fpu_cleanstate). Otherwise we hand over whatever
random values are left in the xmm registers by the last user.
I'm not certain of whether this is excessive paranoia or not, but there was
an outright bug in neglecting to set the mxcsr value that caused awk to
SIGFPE in some case. Especially for Tim Robbins. :-)
i386 probably should do something about the mxcsr setings too.
Found by: tjr
devclass will be present even if the driver was disabled by a hint. Using
device_get_softc() provides the right info even if it's overkill.
Explained by: jhb
