All code that is related to PC BIOS should not be in the Kernel/Firmware
directory as this directory is for abstracted and platform-agnostic code
like ACPI (and device tree parsing in the future).
This fixes a problem with the aarch64 architecure, as these machines
don't have any PC-BIOS in them so actually trying to access these memory
locations (EBDA, BIOS ROM) does not make any sense, as they're specific
to x86 machines only.
Most of the ACPI static parsing methods (methods that can be called
without initializing a full AML parser) are not tied to any specific
platform or CPU architecture.
The only method that is platform-specific is the one that finds the RSDP
structure. Thus, each CPU architecture/platform needs to implement it.
This means that now aarch64 can implement its own method to find the
ACPI RSDP structure, which would be hooked into the rest of the ACPI
code elegantly, but for now I just added a FIXME and that method returns
empty value of Optional<PhysicalAddress>.
This has KString, KBuffer, DoubleBuffer, KBufferBuilder, IOWindow,
UserOrKernelBuffer and ScopedCritical classes being moved to the
Kernel/Library subdirectory.
Also, move the panic and assertions handling code to that directory.
There are now 2 separate classes for almost the same object type:
- EnumerableDeviceIdentifier, which is used in the enumeration code for
all PCI host controller classes. This is allowed to be moved and
copied, as it doesn't support ref-counting.
- DeviceIdentifier, which inherits from EnumerableDeviceIdentifier. This
class uses ref-counting, and is not allowed to be copied. It has a
spinlock member in its structure to allow safely executing complicated
IO sequences on a PCI device and its space configuration.
There's a static method that allows a quick conversion from
EnumerableDeviceIdentifier to DeviceIdentifier while creating a
NonnullRefPtr out of it.
The reason for doing this is for the sake of integrity and reliablity of
the system in 2 places:
- Ensure that "complicated" tasks that rely on manipulating PCI device
registers are done in a safe manner. For example, determining a PCI
BAR space size requires multiple read and writes to the same register,
and if another CPU tries to do something else with our selected
register, then the result will be a catastrophe.
- Allow the PCI API to have a united form around a shared object which
actually holds much more data than the PCI::Address structure. This is
fundamental if we want to do certain types of optimizations, and be
able to support more features of the PCI bus in the foreseeable
future.
This patch already has several implications:
- All PCI::Device(s) hold a reference to a DeviceIdentifier structure
being given originally from the PCI::Access singleton. This means that
all instances of DeviceIdentifier structures are located in one place,
and all references are pointing to that location. This ensures that
locking the operation spinlock will take effect in all the appropriate
places.
- We no longer support adding PCI host controllers and then immediately
allow for enumerating it with a lambda function. It was found that
this method is extremely broken and too much complicated to work
reliably with the new paradigm being introduced in this patch. This
means that for Volume Management Devices (Intel VMD devices), we
simply first enumerate the PCI bus for such devices in the storage
code, and if we find a device, we attach it in the PCI::Access method
which will scan for devices behind that bridge and will add new
DeviceIdentifier(s) objects to its internal Vector. Afterwards, we
just continue as usual with scanning for actual storage controllers,
so we will find a corresponding NVMe controllers if there were any
behind that VMD bridge.
It costs us nothing, and some utilities (such as the known file utility)
rely on the exposed file size (after doing lstat on it), to show
anything useful besides saying the file is "empty".
This class is intended to replace all IOAddress usages in the Kernel
codebase altogether. The idea is to ensure IO can be done in
arch-specific manner that is determined mostly in compile-time, but to
still be able to use most of the Kernel code in non-x86 builds. Specific
devices that rely on x86-specific IO instructions are already placed in
the Arch/x86 directory and are omitted for non-x86 builds.
The reason this works so well is the fact that x86 IO space acts in a
similar fashion to the traditional memory space being available in most
CPU architectures - the x86 IO space is essentially just an array of
bytes like the physical memory address space, but requires x86 IO
instructions to load and store data. Therefore, many devices allow host
software to interact with the hardware registers in both ways, with a
noticeable trend even in the modern x86 hardware to move away from the
old x86 IO space to exclusively using memory-mapped IO.
Therefore, the IOWindow class encapsulates both methods for x86 builds.
The idea is to allow PCI devices to be used in either way in x86 builds,
so when trying to map an IOWindow on a PCI BAR, the Kernel will try to
find the proper method being declared with the PCI BAR flags.
For old PCI hardware on non-x86 builds this might turn into a problem as
we can't use port mapped IO, so the Kernel will gracefully fail with
ENOTSUP error code if that's the case, as there's really nothing we can
do within such case.
For general IO, the read{8,16,32} and write{8,16,32} methods are
available as a convenient API for other places in the Kernel. There are
simply no direct 64-bit IO API methods yet, as it's not needed right now
and is not considered to be Arch-agnostic too - the x86 IO space doesn't
support generating 64 bit cycle on IO bus and instead requires two 2
32-bit accesses. If for whatever reason it appears to be necessary to do
IO in such manner, it could probably be added with some neat tricks to
do so. It is recommended to use Memory::TypedMapping struct if direct 64
bit IO is actually needed.
Until now, our kernel has reimplemented a number of AK classes to
provide automatic internal locking:
- RefPtr
- NonnullRefPtr
- WeakPtr
- Weakable
This patch renames the Kernel classes so that they can coexist with
the original AK classes:
- RefPtr => LockRefPtr
- NonnullRefPtr => NonnullLockRefPtr
- WeakPtr => LockWeakPtr
- Weakable => LockWeakable
The goal here is to eventually get rid of the Lock* classes in favor of
using external locking.
Instead of having two separate implementations of AK::RefCounted, one
for userspace and one for kernelspace, there is now RefCounted and
AtomicRefCounted.
This enforces us to remove duplicated code across the SysFS code. This
results in great simplification of how the SysFS works now, because we
enforce one way to treat SysFSDirectory objects.
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
In a previous commit I moved everything into the new subdirectories in
FileSystem/SysFS directory without trying to actually make changes in
the code itself too much. Now it's time to split the code to make it
more readable and understandable, hence this change occurs now.
Function-local `static constexpr` variables can be `constexpr`. This
can reduce memory consumption, binary size, and offer additional
compiler optimizations.
These changes result in a stripped x86_64 kernel binary size reduction
of 592 bytes.
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.
Using the phrase "create" doesn't give information on whether the object
must be allocated or a failure to do so can be handled gracefully.
Therefore, we must use better phrase for such purpose, so "must_create"
for the allocate-and-construct static methods is definitely good choice.
Instead, allocate before constructing the object and pass NonnullOwnPtr
of KString to the object if needed. Some classes can determine their
names as they have a known attribute to look for or have a static name.
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. :^)
Previously there was a mix of returning plain strings and returning
explicit string views using `operator ""sv`. This change switches them
all to standardized on `operator ""sv` as it avoids a call to strlen.
Both should reside in the SysFS firmware directory which is normally
located in /sys/firmware.
Also, apply some OOM-safety patterns when creating the BIOS and ACPI
directories.
This will somwhat help unify them also under the same SysFS directory in
the commit.
Also, it feels much more like this change reflects the reality that both
ACPI and the BIOS are part of the firmware on x86 computers.
