LUN address is essentially how people used to address SCSI devices back
in the day we had these devices more in use. However, SCSI was taken as
an abstraction layer for many Unix and Unix-like systems, so it still
common to see LUN addresses in use. In Serenity, we don't really provide
such abstraction layer, and therefore until now, we didn't use LUNs too.
However (again), this changes, as we want to let users to address their
devices under SysFS easily. LUNs make sense in that regard, because they
can be easily adapted to different interfaces besides SCSI.
For example, for legacy ATA hard drive being connected to the first IDE
controller which was enumerated on the PCI bus, and then to the primary
channel as slave device, the LUN address would be 0:0:1.
To make this happen, we add unique ID number to each StorageController,
which increments by 1 for each new instance of StorageController. Then,
we adapt the ATA and NVMe devices to use these numbers and generate LUN
in the construction time.
Add a basic NVMe driver support to serenity
based on NVMe spec 1.4.
The driver can support multiple NVMe drives (subsystems).
But in a NVMe drive, the driver can support one controller
with multiple namespaces.
Each core will get a separate NVMe Queue.
As the system lacks MSI support, PIN based interrupts are
used for IO.
Tested the NVMe support by replacing IDE driver
with the NVMe driver :^)
