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. :^)
This change allows the Kernel to actually construct other interfaces
besides the E1000 type.
This solves a breakage that was introduced recently because of move
semantics.
A couple of points on this patch:
1. In current situation, we can waste time to create a KString and throw
it for nothing. This patch ensures we only create it near construction
point so we know we actually need it.
2. It's very likely to assume that non-x86 machines will expose network
device with a device tree (or with ACPI). The raspberry pi machine is a
good example of that. Therefore, each driver should explicitly ask the
correct interface name generation method, and this patch simplifies this
pattern greatly, especially in a case where the same network device can
appear as a PCI device or as device in another bus type on the same
platform target. For example, the (in)famous ne2000 device can be used
either as a PCI device or as an ISA device, depending on the model.
3. In my opinion, it seems much more readable to construct the name near
calling point of the object constructor than to just pass it with move
semantics.
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.
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.
