mknod with mode & S_IFIFO and dev=0 shall behave like mkfifo.
Update the documentation to reflect this state.
Add ATF tests.
This is an in-kernel implementation as typically user-space programs use
mkfifo(2) directly, however whenever there is need to bypass libc (like in
valgrind) then portable POSIX software calls the mknod syscall.
Noted on tech-kern@ by Greg Troxel.
without refresh. If the window is not dirty but the window cursor
position does not match curscr then move the cursor. This fixes
the issues seen in PR lib/54263.
Keep track of the cursor location, if getch is called without a refresh
and without pending updates (dirty windows) then move the cursor to the
correct location directly. Doing this prevents unnecessary refreshes.
Provide three ranges in the conf space: <libnvmm:0-100>, <MI:100-200> and
<MD:200-...>. Remove nvmm_callbacks_register(), and replace it by the conf
op NVMM_MACH_CONF_CALLBACKS, handled by libnvmm. The callbacks are now
per-machine, and the emulators should now do:
- nvmm_callbacks_register(&cbs);
+ nvmm_machine_configure(&mach, NVMM_MACH_CONF_CALLBACKS, &cbs);
This provides more granularity, for example if the process runs two VMs
and wants different callbacks for each.
with all the libpthread symbols in it.
This makes -lpthread behave like to -Wl,--whole-archive -lpthread.
This avoids a situation where threaded static binaries use some libc thread
stubs, which are racy.
Fixes PR lib/54001: call_once2_32, call_once2_static test cases failing on
amd64 since gcc7 import.
Suggested by Jonathan Wakely, thanks!
vcpu_run. This saves a few syscalls and copyins.
For example on Windows 10, moving the mouse from the left to right sides of
the screen generates ~500 events, which now don't result in syscalls.
The error handling is done in vcpu_run and it is less precise, but this
doesn't matter a lot, and will be solved with future NVMM error codes.
Use an intermediate function trampoline to workaround different function
pointer prototypes.
While there, correct scenario returning thrd_nomem from thrd_create(3).
In practice ENOMEM is rarely returned from pthread(3).
Older code worked on tested ports, but was depending on unneeded UB.
The F spec is one of those, it should be terminated with \0 just like all
the others (irrelevant that it has no extra data to delimit).
Fix <sys/mman.h> to define the snprintb() format string correctly (include
the missing \0's). Fix the copy of that definition included into
snprintb(3) to match the updated mman.h version (ride the date bump
from the day before yesterday .. this is the same change, just corrected).
Undo the previous snprintb.c change ("off by one" fix) which was an
attempt to make the broken mman.h usage work (and did, but not the way
it should be done). Also, after using the new * format (instead of only
when something has already matched) skip the associated data so we don't
attempt to interpret it as more field specifiers. This func needs lots of TLC!
Fix the ATF tests for snprintb() to not assume that F format is really
exactly like f format, and has data after the field specifier. It doesn't.
Add several more tests (including testing the '*' field operator
recently added).
introduce a bidirectionnal "comm page", a page of memory shared between
the kernel and userland, and used to transfer data in and out in a more
performant manner than ioctls.
The comm page contains the VCPU state, plus three flags:
- "wanted": the states the kernel must get/set when requested via ioctls
- "cached": the states that are in the comm page
- "commit": the states the kernel must set in vcpu_run
The idea is to avoid performing expensive syscalls, by using the VCPU
state cached, either explicitly or speculatively, in the comm page. For
example, if the state is cached we do a direct 1->5 with no syscall:
+---------------------------------------------+
| Qemu |
+---------------------------------------------+
| ^
| (0) nvmm_vcpu_getstate | (6) Done
| |
V |
+---------------------------------------+
| libnvmm |
+---------------------------------------+
| ^ | ^
(1) State | | (2) No | (3) Ioctl: | (5) Ok, state
cached? | | | "please cache | fetched
| | | the state" |
V | | |
+-----------+ | |
| Comm Page |------+---------------+
+-----------+ |
^ |
(4) "Alright | V
babe" | +--------+
+-----| Kernel |
+--------+
The main changes in behavior are:
- nvmm_vcpu_getstate(): won't emit a syscall if the state is already
cached in the comm page, will just fetch from the comm page directly
- nvmm_vcpu_setstate(): won't emit a syscall at all, will just cache
the wanted state in the comm page
- nvmm_vcpu_run(): will commit the to-be-set state in the comm page,
as previously requested by nvmm_vcpu_setstate()
In addition to this, the kernel NVMM driver is changed to speculatively
cache certain states known to be of interest, so that the future
nvmm_vcpu_getstate() calls libnvmm or the emulator will perform will use
the comm page rather than expensive syscalls. For example, if an I/O
VMEXIT occurs, the I/O Assist in libnvmm will want GPRS+SEGS+CRS+MSRS,
and now the kernel caches all of that in the comm page before returning
to userland.
Overall, in a normal run of Windows 10, this saves several millions of
syscalls. Eg on a 4CPU Intel with 4VCPUs, booting the Win10 install ISO
goes from taking 1min35 to taking 1min16.
The libnvmm API is not changed, but the ABI is. If we changed the API it
would be possible to save expensive memcpys on libnvmm's side. This will
be avoided in a future version. The comm page can also be extended to
implement future services.
wiz