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
Otherwise, the setting of the PG_M bit by one processor could be lost if
another processor is simultaneously changing the PG_W bit.
Reviewed by: tegge@
present and thus that the PnPBIOS probe should be skipped instead of
having ACPI zero out the PnPBIOStable pointer.
- Make the PnPBIOStable pointer static to i386/i386/bios.c now that that is
the only place it is used.
pmap_extract() already does it.
In pmap_enter(), opa has already been masked so don't do it again.
Wrap a long line (recent transgression).
Use trunc_page() in pmap_mapdev() instead of anding with PG_FRAME, since
that is what we really meant.
Submitted by: alc (first item)
- export the rest of the cpu features (and amd's features).
- turn on EFER_NXE, depending on the NX amd feature bit
- reorg the identcpu stuff a bit in order to stop treating the
amd features as second class features (since it is now a primary feature
bit set) and make it easier to export.
lives in the top 12 'available' bits. atop() in the PHYS_TO_VM_PAGE()
macro only masks off the lower bits (by accident) and the upper bits
in the 64 bit ptes turn into "interesting" index values.
pmap_remove() would be called with a huge range and we'd stride across
it in only 2MB chunks. This would manifest as massive cpu time and a
largely unresponsive system during hard swap. Instead, check the higher
page directories which means we can run pmap_remove() in just a few
hundred loop iterations instead of millions since we can process
address space in chunks of 512GB and 1GB as well as 2MB.
Eternal thanks to: tmm
of this micro-optimization occurs when we call pmap_enter() to wire an
already mapped page. Because of the micro-optimization, we fail to
mark the PTE as wired. Later, on teardown of the address space,
pmap_remove_pages() destroys the PTE before vm_fault_unwire() has
unwired the page. (pmap_remove_pages() is not supposed to destroy
wired PTEs. They are destroyed by a later call to pmap_remove().)
Thus, the page becomes lost.
Note: The page is not lost if the application called munlock(2), only
if it relies on teardown of the address space to unwire its pages.
For the historically inclined, this bug was introduced by a
megacommit, revision 1.182, roughly six years ago.
Leak observed by: green@ and dillon independently
Patch submitted by: dillon at backplane dot com
Reviewed by: tegge@
MFC after: 1 week
gmon and struct gmonhdr was originally just to represent the kernel
(profiling) clock frequency and it remains poorly suited to representing
the frequencies of fast counters like the TSC. It broke a year or two
ago. This quick fix keeps it working for another year or month or two
until TSC frequencies can exceed 2^32, by dividing the frequency by 2.
Dividing the frequency by 4 would work for a little longer but would
lose a little too much precision.
ordinary functions, essentially by backing out half of rev.1.115 of
amd64/exception.S. The handlers must be between certain labels for
the purposes of profiling, and this was broken by scattering them in
separately compiled .S files, especially for ordinary functions that
ended up between the labels. Merge the files by #including them as
before, except with different pathnames and better comments and
organization. Changes to the scattered files are minimal -- just
move the labels to the file that does the #includes.
This also partly fixes profiling of IPIs -- all IPI handlers are now
correctly classified as interrupt handlers, but many are still missing
mcount calls.
- perfmon headers must be avoided until perfmon is supported.
- all call-used registers including return registers must be preserved
by .mcount(), etc., not quite as in profile.h. __cyg_profile_func_*()
don't require this, but they are (mis)implemented as aliases for
.mcount(), etc. so they preserve the registers.
- i386 ifdefs related to perfmon have not been adjusted yet.
amd64 as necessary. This is routine, except:
- the FAKE_MCOUNT($bintr) in doreti was missing the '$'. This gave a
a garbage address made up of padding bytes (with the nop byte 0x90 as
the MSB) instead of the intended address of bintr. This accidentally
worked on i386's because (0x90 << 24) is close enough to bintr, but
it doesn't work on amd64's because (0x90 << 56) is much further away
from bintr.
- the FAKE_MCOUNT($btrap) in calltrap was similarly broken. It hasn't
been needed since FreeBSD-1, so just delete it.
and high resolution profiling of interrupt handlers. The adjustments
are routine once the magic stack offset 13*4 is decoded to be TF_RIP
(there were originally more types of stack frames so using TF_EIP for
one of them wouldn't have been much simpler).
Removed garbage comments attached to some of the FAKE_MCOUNT()s.
that the usual macro for "ret" hides the detail of calling .mexitcount
before returning.
Fixed missing call to .mexitcount in lgdt(). This was missing on
i386's, mainly because lgdt() uses lret[q] insted of ret. This is
very unimportant since lgdt() is not (normally?) called until after
profiling is initialized.
and improved some comments). Also, made the documented {f,s}uword()
functions the standard entry points and the undocumented {f,s}uword64()
functions alternative entry points, like {f,s}uword32() for i386's. The
bitrot in the comments was a little larger here -- there are new undocumented
32-bit sub-word functions, not just renaming of 16-bit functions from
documented ones to undocumented ones.
to <sys/gmon.h>. Cleaned them up a little by not attempting to ifdef
for incomplete and out of date support for GUPROF in userland, as in
the sparc64 version.
different context support for 32 vs 64 bit processes. This simply omits
the save/restore of the segment selector registers for non 32 bit
processes. This avoids the rdmsr/rwmsr juggling when restoring %gs
clobbers the kernel msr that holds the gsbase.
However, I suspect it might be better to conditionally do this at
user<->kernel transition where we wouldn't need to do the juggling in the
first place. Or have per-thread extended context save/restore hooks.
to help the AMD cpus (which have a hardware tlb flush filter). I held
off to see what the 64 bit Intel cpus did, but it doesn't seem to help
much there either. Oh well, store it in the Attic.
elf_reloc() backends for two reasons. First, to support the possibility
of there being two elf linkers in the kernel (eg: amd64), and second, to
pass the relocbase explicitly (for relocating .o format kld files).
individual asm versions. The global lock is shared between the BIOS and
OS and thus cannot use our mutexes. It is defined in section 5.2.9.1 of
the ACPI specification.
Reviewed by: marcel, bde, jhb
register controlled the trigger mode and polarity of EISA interrupts.
However, it appears that most (all?) PCI systems use the ELCR to manage
the trigger mode and polarity of ISA interrupts as well since ISA IRQs used
to route PCI interrupts need to be level triggered with active low
polarity. We check to see if the ELCR exists by sanity checking the value
we get back ensuring that IRQS 0 (8254), 1 (atkbd), 2 (the link from the
slave PIC), and 8 (RTC) are all clear indicating edge trigger and active
high polarity.
This mini-driver will be used by the atpic driver to manage the trigger and
polarity of ISA IRQs. Also, the mptable parsing code will use this mini
driver rather than examining the ELCR directly.
move its declaration to the machine-dependent header file on those
machines that use it. In principle, only i386 should have it.
Alpha and AMD64 should use their direct virtual-to-physical mapping.
- Remove pmap_kenter_temporary() from ia64. It is unused. Approved
by: marcel@
Report the %ecx bits in cpuid function 1. This is a hack.
When reporting AMD Features, only mask off the common bits. Otherwise
the SEP bit masks off SYSCALL etc in the report.
level of abstraction for any and all CPU mask and CPU bitmap variables
so that platforms have the ability to break free from the hard limit
of 32 CPUs, simply because we don't have more bits in an u_int. Note
that the type is not supposed to solve massive parallelism, where
the number of CPUs can be larger than the width of the widest integral
type. As such, cpumask_t is not supposed to be a compound type. If
such would be necessary in the future, we can deal with the issues
then and there. For now, it can be assumed that the type is integral
and unsigned.
With this commit, all MD definitions start off as u_int. This allows
us to phase-in cpumask_t at our leasure without breaking anything.
Once cpumask_t is used consistently, platforms can switch to wider
(or smaller) types if such would be beneficial (or not; whatever :-)
Compile-tested on: i386
dependent function by the same name and a machine-independent function,
sf_buf_mext(). Aside from the virtue of making more of the code machine-
independent, this change also makes the interface more logical. Before,
sf_buf_free() did more than simply undo an sf_buf_alloc(); it also
unwired and if necessary freed the page. That is now the purpose of
sf_buf_mext(). Thus, sf_buf_alloc() and sf_buf_free() can now be used
as a general-purpose emphemeral map cache.
all the ancient Intel/VIA/SIS/etc chipsets on amd64 systems. Even the
newer intel stuff won't need this since we use acpi by default and we
don't have all their magic programming information. Just use a generic
"Host to PCI bridge" name if we ever hit this code.
to build the kernel. It doesn't affect the operation if gcc.
Most of the changes are just adding __INTEL_COMPILER to #ifdef's, as
icc v8 may define __GNUC__ some parts may look strange but are
necessary.
Additional changes:
- in_cksum.[ch]:
* use a generic C version instead of the assembly version in the !gcc
case (ASM code breaks with the optimizations icc does)
-> no bad checksums with an icc compiled kernel
Help from: andre, grehan, das
Stolen from: alpha version via ppc version
The entire checksum code should IMHO be replaced with the DragonFly
version (because it isn't guaranteed future revisions of gcc will
include similar optimizations) as in:
---snip---
Revision Changes Path
1.12 +1 -0 src/sys/conf/files.i386
1.4 +142 -558 src/sys/i386/i386/in_cksum.c
1.5 +33 -69 src/sys/i386/include/in_cksum.h
1.5 +2 -0 src/sys/netinet/igmp.c
1.6 +0 -1 src/sys/netinet/in.h
1.6 +2 -0 src/sys/netinet/ip_icmp.c
1.4 +3 -4 src/contrib/ipfilter/ip_compat.h
1.3 +1 -2 src/sbin/natd/icmp.c
1.4 +0 -1 src/sbin/natd/natd.c
1.48 +1 -0 src/sys/conf/files
1.2 +0 -1 src/sys/conf/files.amd64
1.13 +0 -1 src/sys/conf/files.i386
1.5 +0 -1 src/sys/conf/files.pc98
1.7 +1 -1 src/sys/contrib/ipfilter/netinet/fil.c
1.10 +2 -3 src/sys/contrib/ipfilter/netinet/ip_compat.h
1.10 +1 -1 src/sys/contrib/ipfilter/netinet/ip_fil.c
1.7 +1 -1 src/sys/dev/netif/txp/if_txp.c
1.7 +1 -1 src/sys/net/ip_mroute/ip_mroute.c
1.7 +1 -2 src/sys/net/ipfw/ip_fw2.c
1.6 +1 -2 src/sys/netinet/igmp.c
1.4 +158 -116 src/sys/netinet/in_cksum.c
1.6 +1 -1 src/sys/netinet/ip_gre.c
1.7 +1 -2 src/sys/netinet/ip_icmp.c
1.10 +1 -1 src/sys/netinet/ip_input.c
1.10 +1 -2 src/sys/netinet/ip_output.c
1.13 +1 -2 src/sys/netinet/tcp_input.c
1.9 +1 -2 src/sys/netinet/tcp_output.c
1.10 +1 -1 src/sys/netinet/tcp_subr.c
1.10 +1 -1 src/sys/netinet/tcp_syncache.c
1.9 +1 -2 src/sys/netinet/udp_usrreq.c
1.5 +1 -2 src/sys/netinet6/ipsec.c
1.5 +1 -2 src/sys/netproto/ipsec/ipsec.c
1.5 +1 -1 src/sys/netproto/ipsec/ipsec_input.c
1.4 +1 -2 src/sys/netproto/ipsec/ipsec_output.c
and finally remove
sys/i386/i386 in_cksum.c
sys/i386/include in_cksum.h
---snip---
- endian.h:
* DTRT in C++ mode
- quad.h:
* we don't use gcc v1 anymore, remove support for it
Suggested by: bde (long ago)
- assym.h:
* avoid zero-length arrays (remove dependency on a gcc specific
feature)
This change changes the contents of the object file, but as it's
only used to generate some values for a header, and the generator
knows how to handle this, there's no impact in the gcc case.
Explained by: bde
Submitted by: Marius Strobl <marius@alchemy.franken.de>
- aicasm.c:
* minor change to teach it about the way icc spells "-nostdinc"
Not approved by: gibbs (no reply to my mail)
- bump __FreeBSD_version (lang/icc needs to know about the changes)
Incarnations of this patch survive gcc compiles since a loooong time,
I use it on my desktop. An icc compiled kernel works since Nov. 2003
(exceptions: snd_* if used as modules), it survives a build of the
entire ports collection with icc.
Parts of this commit contains suggestions or submissions from
Marius Strobl <marius@alchemy.franken.de>.
Reviewed by: -arch
Submitted by: netchild
in the non-_KERNEL case. This "fixes" applications that include
this "kernel-only" header and also include <strings.h> (or get
<strings.h> via the default _BSD_VISIBLE pollution in <string.h>.
In C++ there was a fatal error: the declaration specifies C linkage
but the implementation gives C++ linkage. In C there was only a
static/extern mismatch if the headers were included in a certain order
order, and a partially redundant declaration for all include orders;
gcc emits incomplete or wrong diagnostics for these, but only for
compiling with -Wsystem-headers and certain other warning options, so
the problem was usually not seen for C.
Ports breakage reported by: kris
ever since alpha/alpha/pmap.c revision 1.81 introduced the list allpmaps,
there has been no reason for having this function on Alpha. Briefly,
when pmap_growkernel() relied upon the list of all processes to find and
update the various pmaps to reflect a growth in the kernel's valid
address space, pmap_init2() served to avoid a race between pmap
initialization and pmap_growkernel(). Specifically, pmap_pinit2() was
responsible for initializing the kernel portions of the pmap and
pmap_pinit2() was called after the process structure contained a pointer
to the new pmap for use by pmap_growkernel(). Thus, an update to the
kernel's address space might be applied to the new pmap unnecessarily,
but an update would never be lost.
Introduce d_version field in struct cdevsw, this must always be
initialized to D_VERSION.
Flip sense of D_NOGIANT flag to D_NEEDGIANT, this involves removing
four D_NOGIANT flags and adding 145 D_NEEDGIANT flags.
to catch are already nicely caught by trapping the null pointer derefs.
Remove no-longer-used noswitch/nothrow strings. They were referenced
by the stub cpu_switch() etc functions before they were implemented.
Try something a little different for the lock prefixes.
Prompted by: bde (the first two items anyway)
updated for the regparm ABI on amd64.
Context switch debug regs.
Update for fpu simplification
Don't needlessly reload %cr3, in case the cpu has the tlb flush filter
turned off. Re-add LAZY_SWITCH stubs.
