This new subsystem includes better abstractions of how time will be
handled in the OS. We take advantage of the existing RTC timer to aid
in keeping time synchronized. This is standing in contrast to how we
handled time-keeping in the kernel, where the PIT was responsible for
that function in addition to update the scheduler about ticks.
With that new advantage, we can easily change the ticking dynamically
and still keep the time synchronized.
In the process context, we no longer use a fixed declaration of
TICKS_PER_SECOND, but we call the TimeManagement singleton class to
provide us the right value. This allows us to use dynamic ticking in
the future, a feature known as tickless kernel.
The scheduler no longer does by himself the calculation of real time
(Unix time), and just calls the TimeManagment singleton class to provide
the value.
Also, we can use 2 new boot arguments:
- the "time" boot argument accpets either the value "modern", or
"legacy". If "modern" is specified, the time management subsystem will
try to setup HPET. Otherwise, for "legacy" value, the time subsystem
will revert to use the PIT & RTC, leaving HPET disabled.
If this boot argument is not specified, the default pattern is to try
to setup HPET.
- the "hpet" boot argumet accepts either the value "periodic" or
"nonperiodic". If "periodic" is specified, the HPET will scan for
periodic timers, and will assert if none are found. If only one is
found, that timer will be assigned for the time-keeping task. If more
than one is found, both time-keeping task & scheduler-ticking task
will be assigned to periodic timers.
If this boot argument is not specified, the default pattern is to try
to scan for HPET periodic timers. This boot argument has no effect if
HPET is disabled.
In hardware context, PIT & RealTimeClock classes are merely inheriting
from the HardwareTimer class, and they allow to use the old i8254 (PIT)
and RTC devices, managing them via IO ports. By default, the RTC will be
programmed to a frequency of 1024Hz. The PIT will be programmed to a
frequency close to 1000Hz.
About HPET, depending if we need to scan for periodic timers or not,
we try to set a frequency close to 1000Hz for the time-keeping timer
and scheduler-ticking timer. Also, if possible, we try to enable the
Legacy replacement feature of the HPET. This feature if exists,
instructs the chipset to disconnect both i8254 (PIT) and RTC.
This behavior is observable on QEMU, and was verified against the source
code:
ce967e2f33
The HPETComparator class is inheriting from HardwareTimer class, and is
responsible for an individual HPET comparator, which is essentially a
timer. Therefore, it needs to call the singleton HPET class to perform
HPET-related operations.
The new abstraction of Hardware timers brings an opportunity of more new
features in the foreseeable future. For example, we can change the
callback function of each hardware timer, thus it makes it possible to
swap missions between hardware timers, or to allow to use a hardware
timer for other temporary missions (e.g. calibrating the LAPIC timer,
measuring the CPU frequency, etc).
Also, duplicate data in dbg() and klog() calls were removed.
In addition, leakage of virtual address to kernel log is prevented.
This is done by replacing kprintf() calls to dbg() calls with the
leaked data instead.
Also, other kprintf() calls were replaced with klog().
You can now mmap a file as private and writable, and the changes you
make will only be visible to you.
This works because internally a MAP_PRIVATE region is backed by a
unique PrivateInodeVMObject instead of using the globally shared
SharedInodeVMObject like we always did before. :^)
Fixes#1045.
Now we check before we set a FBResolution if the BXVGA device is capable
of setting the requested resolution.
If not, we revert the resolution to the previous one and return an error
to userspace.
Fixes#451.
Also, update the class implementation to use PCI::Device class
accordingly.
The create() helper will now search for an IDE controller in the
PCI bus, allowing to simplify the initialize() method.
This was only used by HashTable::dump() which I used when doing the
first HashTable implementation. Removing this allows us to also remove
most includes of <AK/kstdio.h>.
We add this feature together with the VMWareBackdoor class.
VMWareBackdoor class is responsible for enabling the vmmouse, and then
controlling it from the PS2 mouse IRQ handler.
There's no sense in allowing arbitrarily huge resolutions. Instead, we
now cap the screen size at 4K DCI resolution and will reject attempts
to go bigger with EINVAL.
Previously it was not possible for this function to fail. You could
exploit this by triggering the creation of a VMObject whose physical
memory range would wrap around the 32-bit limit.
It was quite easy to map kernel memory into userspace and read/write
whatever you wanted in it.
Test: Kernel/bxvga-mmap-kernel-into-userspace.cpp
System components that need an IRQ handling are now inheriting the
InterruptHandler class.
In addition to that, the initialization process of PATAChannel was
changed to fit the changes.
PATAChannel, E1000NetworkAdapter and RTL8139NetworkAdapter are now
inheriting from PCI::Device instead of InterruptHandler directly.
When using dbg() in the kernel, the output is automatically prefixed
with [Process(PID:TID)]. This makes it a lot easier to understand which
thread is generating the output.
This patch also cleans up some common logging messages and removes the
now-unnecessary "dbg() << *current << ..." pattern.
