The previous allocator was very naive and kept the state of all pages
in one big bitmap. When allocating, we had to scan through the bitmap
until we found an unset bit.
This patch introduces a new binary buddy allocator that manages the
physical memory pages.
Each PhysicalRegion is divided into zones (PhysicalZone) of 16MB each.
Any extra pages at the end of physical RAM that don't fit into a 16MB
zone are turned into 15 or fewer 1MB zones.
Each zone starts out with one full-sized block, which is then
recursively subdivided into halves upon allocation, until a block of
the request size can be returned.
There are more opportunities for improvement here: the way zone objects
are allocated and stored is non-optimal. Same goes for the allocation
of buddy block state bitmaps.
This involves refactoring VirtIOConsole into VirtIOConsole and
VirtIOConsolePort. VirtIOConsole is the VirtIODevice, it owns multiple
VirtIOConsolePorts as well as two control queues. Each
VirtIOConsolePort is a CharacterDevice.
This replaces all uses of LexicalPath in the Kernel with the functions
from KLexicalPath. This also allows the Kernel to stop including
AK::LexicalPath.
This adds KLexicalPath, which are a few static functions which aim to
mostly emulate AK::LexicalPath. They are however constrained to work
with absolute paths only, containing no '.' or '..' path segments and no
consecutive slashes. This way, it is possible to avoid use StringView
for the return values and thus avoid allocating new String objects.
As explained above, the functions are currently very strict about the
allowed input paths. This seems to not be a problem currently. Since the
functions VERIFY this, potential bugs caused by this will become
immediately obvious.
Instead of using one file for the entire "backend" of the ProcFS data
and metadata, we could split that file into two files that represent
2 logical chunks of the ProcFS exposed objects:
1. Global and inter-process information. This includes all fixed data in
the root folder of the ProcFS, networking information and the bus
folder.
2. Per-process information. This includes all dynamic data about a
process that resides in the /proc/PID/ folder.
This change makes it more easier to read the code and to change it,
hence we do it although there's no technical benefit from it now :)
The new ProcFS design consists of two main parts:
1. The representative ProcFS class, which is derived from the FS class.
The ProcFS and its inodes are much more lean - merely 3 classes to
represent the common type of inodes - regular files, symbolic links and
directories. They're backed by a ProcFSExposedComponent object, which
is responsible for the functional operation behind the scenes.
2. The backend of the ProcFS - the ProcFSComponentsRegistrar class
and all derived classes from the ProcFSExposedComponent class. These
together form the entire backend and handle all the functions you can
expect from the ProcFS.
The ProcFSExposedComponent derived classes split to 3 types in the
manner of lifetime in the kernel:
1. Persistent objects - this category includes all basic objects, like
the root folder, /proc/bus folder, main blob files in the root folders,
etc. These objects are persistent and cannot die ever.
2. Semi-persistent objects - this category includes all PID folders,
and subdirectories to the PID folders. It also includes exposed objects
like the unveil JSON'ed blob. These object are persistent as long as the
the responsible process they represent is still alive.
3. Dynamic objects - this category includes files in the subdirectories
of a PID folder, like /proc/PID/fd/* or /proc/PID/stacks/*. Essentially,
these objects are always created dynamically and when no longer in need
after being used, they're deallocated.
Nevertheless, the new allocated backend objects and inodes try to use
the same InodeIndex if possible - this might change only when a thread
dies and a new thread is born with a new thread stack, or when a file
descriptor is closed and a new one within the same file descriptor
number is opened. This is needed to actually be able to do something
useful with these objects.
The new design assures that many ProcFS instances can be used at once,
with one backend for usage for all instances.
The intention is to add dynamic mechanism for notifying the userspace
about hotplug events. Currently, the DMI (SMBIOS) blobs and ACPI tables
are exposed in the new filesystem.
Neither the kernel nor LibELF support loading libraries with larger
PT_LOAD alignment. The default on x86 is 4096 while it's 2MiB on x86_64.
This changes the alignment to 4096 on all platforms.
Currently, Kernel::Graphics::FramebufferConsole is written assuming that
the underlying framebuffer memory exists in physically contiguous
memory. There are a bunch of framebuffer devices that would need to use
the components of FramebufferConsole (in particular access to the kernel
bitmap font rendering logic). To reduce code duplication, framebuffer
console has been split into two parts, the abstract
GenericFramebufferConsole class which does the rendering, and the
ContiguousFramebufferConsole class which contains all logic related to
managing the underling vm object.
Also, a new flush method has been added to the class, to support devices
that require an extra flush step to render.
Multiboot only supports ELF32 executables. This changes the build
process to build an ELF32 executable which has a 32-bit entry point,
but consists of mostly 64-bit code.
This adds just enough stubs to make the kernel compile on x86_64. Obviously
it won't do anything useful - in fact it won't even attempt to boot because
Multiboot doesn't support ELF64 binaries - but it gets those compiler errors
out of the way so more progress can be made getting all the missing
functionality in place.
This doesn't really matter in terms of writability for the kernel text
because we set up proper page mappings anyway which prohibit writing
to the text segment. However, this makes the profiler happy which
previously died when validating the kernel's ELF program headers.
These are the actual structures that allow USB to work (i.e the ones
actually defined in the specification). This should provide us enough
of a baseline implementation that we can build on to support
different types of USB device.
These are pretty common on older LGA1366 & LGA1150 motherboards.
NOTE: Since the registers datasheets for all versions of the chip
besides versions 1 - 3 are still under NDAs i had to collect
several "magical vendor constants" from the *BSD driver and the
linux driver that i was not able to name verbosely, and as such
these are labeled with the comment "vendor magic values".
We call it E1000E, because the layout for these cards is somewhat not
the same like E1000 supported cards.
Also, this card supports advanced features that are not supported on
8254x cards.
Instead of initializing network adapters in init.cpp, let's move that
logic into a separate class to handle this.
Also, it seems like a good idea to shift responsiblity on enumeration
of network adapters after the boot process, so this singleton will take
care of finding the appropriate network adapter when asked to with an
IPv4 address or interface name.
With this change being merged, we simplify the creation logic of
NetworkAdapter derived classes, so we enumerate the PCI bus only once,
searching for driver candidates when doing so, and we let each driver
to test if it is resposible for the specified PCI device.
Previously we'd incur the costs for a function call via the PLT even
for the most trivial ref-count actions like increasing/decreasing the
reference count.
By moving the code to the header file we allow the compiler to inline
this code into the caller's function.
This is a simple string class for use in the kernel. It encapsulates
a length + character array in a single-allocation object.
Main differences from AK::String:
- Single-owner (no reference counting.)
- Allocation failures are exposed, not hidden.
The basic idea is to allow better and more precise string management
in the kernel.
It seems like overly-specific classes were written for no good reason.
Instead of making each adapter to have its own unique FramebufferDevice
class, let's generalize everything to keep implementation more
consistent.
When debugging kernel code, it's necessary to set extra flags. Normal
advice is to set -ggdb3. Sometimes that still doesn't provide enough
debugging information for complex functions that still get optimized.
Compiling with -Og gives the best optimizations for debugging, but can
sometimes be broken by changes that are innocuous when the compiler gets
more of a chance to look at them. The new CMake option enables both
compile options for kernel code.
This had very bad interactions with ccache, often leading to rebuilds
with 100% cache misses, etc. Ali says it wasn't that big of a speedup
in the end anyway, so let's not bother with it.
We can always bring it back in the future if it seems like a good idea.
This simple driver simply finds a device in a device definitions list
and then sets up a SerialDevice instance based on the definition.
The driver currently only supports "WCH CH382 2S" pci serial boards,
as that is the only device available for me to test with, but most
other pci serial devices should be as easily addable as adding a
board_definitions entry.
As we removed the support of VBE modesetting that was done by GRUB early
on boot, we need to determine if we can modeset the resolution with our
drivers, and if not, we should enable text mode and ensure that
SystemServer knows about it too.
Also, SystemServer should first check if there's a framebuffer device
node, which is an indication that text mode was not even if it was
requested. Then, if it doesn't find it, it should check what boot_mode
argument the user specified (in case it's self-test). This way if we
try to use bochs-display device (which is not VGA compatible) and
request a text mode, it will not honor the request and will continue
with graphical mode.
Also try to print critical messages with mininum memory allocations
possible.
In LibVT, We make the implementation flexible for kernel-specific
methods that are implemented in ConsoleImpl class.
