When GraphicsManagement initializes the drivers we can disable the
bootloader framebuffer console. Right now we don't yet fully destroy
the no longer needed console as it may be in use by another CPU.
Apologies for the enormous commit, but I don't see a way to split this
up nicely. In the vast majority of cases it's a simple change. A few
extra places can use TRY instead of manual error checking though. :^)
This mostly just moved the problem, as a lot of the callers are not
capable of propagating the errors themselves, but it's a step in the
right direction.
We now use AK::Error and AK::ErrorOr<T> in both kernel and userspace!
This was a slightly tedious refactoring that took a long time, so it's
not unlikely that some bugs crept in.
Nevertheless, it does pass basic functionality testing, and it's just
real nice to finally see the same pattern in all contexts. :^)
We create a base class called GenericFramebufferDevice, which defines
all the virtual functions that must be implemented by a
FramebufferDevice. Then, we make the VirtIO FramebufferDevice and other
FramebufferDevice implementations inherit from it.
The most important consequence of rearranging the classes is that we now
have one IOCTL method, so all drivers should be committed to not
override the IOCTL method or make their own IOCTLs of FramebufferDevice.
All graphical IOCTLs are known to all FramebufferDevices, and it's up to
the specific implementation whether to support them or discard them (so
we require extensive usage of KResult and KResultOr, together with
virtual characteristic functions).
As a result, the interface is much cleaner and understandable to read.
We never used that type method except in initialization in
GraphicsManagement, and we used it there to query whether the device is
VGA compatible or not.
Instead of blindly forcing BGR format on the bochs-display device, let's
ensure we do that only on QEMU bochs-display and not on VirtualBox
graphics adapter too.
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.
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.
