Instead of doing so in the constructor, let's do immediately after the
constructor, so we can safely pass a reference of a Device, so the
SysFSDeviceComponent constructor can use that object to identify whether
it's a block device or a character device.
This allows to us to not hold a device in SysFSDeviceComponent with a
RefPtr.
Also, we also call the before_removing method in both SlavePTY::unref
and File::unref, so because Device has that method being overrided, it
can ensure the device is removed always cleanly.
These methods are no longer needed because SystemServer is able to
populate the DevFS on its own.
Device absolute_path no longer assume a path to the /dev location,
because it really should not assume any path to a Device node.
Because StorageManagement still needs to know the storage name, we
declare a virtual method only for StorageDevices to override, but this
technique should really be removed later on.
A couple of things were changed:
1. Semantic changes - PCI segments are now called PCI domains, to better
match what they are really. It's also the name that Linux gave, and it
seems that Wikipedia also uses this name.
We also remove PCI::ChangeableAddress, because it was used in the past
but now it's no longer being used.
2. There are no WindowedMMIOAccess or MMIOAccess classes anymore, as
they made a bunch of unnecessary complexity. Instead, Windowed access is
removed entirely (this was tested, but never was benchmarked), so we are
left with IO access and memory access options. The memory access option
is essentially mapping the PCI bus (from the chosen PCI domain), to
virtual memory as-is. This means that unless needed, at any time, there
is only one PCI bus being mapped, and this is changed if access to
another PCI bus in the same PCI domain is needed. For now, we don't
support mapping of different PCI buses from different PCI domains at the
same time, because basically it's still a non-issue for most machines
out there.
2. OOM-safety is increased, especially when constructing the Access
object. It means that we pre-allocating any needed resources, and we try
to find PCI domains (if requested to initialize memory access) after we
attempt to construct the Access object, so it's possible to fail at this
point "gracefully".
3. All PCI API functions are now separated into a different header file,
which means only "clients" of the PCI subsystem API will need to include
that header file.
4. Functional changes - we only allow now to enumerate the bus after
a hardware scan. This means that the old method "enumerate_hardware"
is removed, so, when initializing an Access object, the initializing
function must call rescan on it to force it to find devices. This makes
it possible to fail rescan, and also to defer it after construction from
both OOM-safety terms and hotplug capabilities.
This expands the reach of error propagation greatly throughout the
kernel. Sadly, it also exposes the fact that we're allocating (and
doing other fallible things) in constructors all over the place.
This patch doesn't attempt to address that of course. That's work for
our future selves.
This ensures we safely handle interrupts (which can call virtual
functions), so they don't happen in the constructor - this pattern can
lead to a crash, if we are still in the constructor context because
not all methods are available for usage (some are pure virtual,
so it's possible to call __cxa_pure_virtual).
Also, under some conditions like adding a PCI device via PCI-passthrough
mechanism in QEMU, it became exposed to the eye that the code asserts on
RNG::handle_device_config_change(). That device has no configuration but
if the hypervisor still misbehaves and tries to configure it, we should
simply return false to indicate nothing happened.
Before of this change, many specific classes to VirtIO were in the
Kernel namespace, which polluted it.
Everything should be more organized now, but there's still room for
improvement later.
This class member was used only to determine the device type when
printing messages to the debug log. Instead, remove this class member,
and add a quick way to find the device type according to how the VirtIO
specification says to do that.
This simplifies construction of VirtIODevices a bit, because now the
constructor doesn't need to ask for a String identified with the device
type.
Now that the old PCI::Device was removed, we can complete the PCI
changes by making the PCI::DeviceController to be named PCI::Device.
Really the entire purpose and the distinction between the two was about
interrupts, but since this is no longer a problem, just rename it to
simplify things further.
This makes for nicer handling of errors compared to checking whether a
RefPtr is null. Additionally, this will give way to return different
types of errors in the future.
...and also RangeAllocator => VirtualRangeAllocator.
This clarifies that the ranges we're dealing with are *virtual* memory
ranges and not anything else.
It's easy to forget the responsibility of validating and safely copying
kernel parameters in code that is far away from syscalls. ioctl's are
one such example, and bugs there are just as dangerous as at the root
syscall level.
To avoid this case, utilize the AK::Userspace<T> template in the ioctl
kernel interface so that implementors have no choice but to properly
validate and copy ioctl pointer arguments.
We don't need to have a dedicated API for creating a VMObject with a
single page, the multi-page API option works in all cases.
Also make the API take a Span<NonnullRefPtr<PhysicalPage>> instead of
a NonnullRefPtrVector<PhysicalPage>.
It is not legal to resize a VMObject after it has been created.
As far as I can tell, this code would never actually run since the
object was already populated with physical pages due to using
AllocationStrategy::AllocateNow.
The spec requires a flush after setting the new buffer resource id,
which is required by QEMUs SDL backend but not the GTK backend. This
brings us in line with the spec and makes it work for the SDL backend.
Some devices may require DMA transfers to flush the updated buffer
areas prior to flipping. For those devices we track the areas that
require flushing prior to the next flip. For devices that do not
support flipping, but require flushing, we'll simply flush after
updating the front buffer.
This also adds a small optimization that skips these steps entirely for
a screen that doesn't have any updates that need to be rendered.
We use a switch-case statements to ensure we try to find the best
suitable driver for a specific graphics card. In case we don't find
such, we use the default statement to initialize the graphics card as a
generic VGA adapter, if the adapter is VGA compatible.
If we couldn't initialize the driver, we don't touch this adapter
anymore.
Also, GraphicsDevice should not be tied to a PCI::Address member, as it
can be theortically be used with other buses (e.g. ISA cards).
We regularily need to flush many rectangles, so instead of making many
expensive ioctl() calls to the framebuffer driver, collect the
rectangles and only make one call. And if we have too many rectangles
then it may be cheaper to just update the entire region, in which case
we simply convert them all into a union and just flush that one
rectangle instead.
This creates /dev/fbX devices for each physical output, owned by the
parent VirtIOGPU instance. This allows mapping and setting resolutions
independently for each output.
