Since devices are enumerable and can compute their own name inside the
/dev hierarchy, there is no need to try and parse "root=/dev/xxx" by
hand.
This also makes any block device a candidate for the boot device, which
now includes ramdisk devices, so SerenityOS can now boot diskless too.
The disk image generated for QEMU is suitable, as long as it fits in
memory with room to spare for the rest of the system.
Problem:
- Many constructors are defined as `{}` rather than using the ` =
default` compiler-provided constructor.
- Some types provide an implicit conversion operator from `nullptr_t`
instead of requiring the caller to default construct. This violates
the C++ Core Guidelines suggestion to declare single-argument
constructors explicit
(https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit).
Solution:
- Change default constructors to use the compiler-provided default
constructor.
- Remove implicit conversion operators from `nullptr_t` and change
usage to enforce type consistency without conversion.
When ProcFS could no longer allocate KBuffer objects to serve calls to
read, it would just return 0, indicating EOF. This then triggered
parsing errors because code assumed it read the file.
Because read isn't supposed to return ENOMEM, change ProcFS to populate
the file data upon file open or seek to the beginning. This also means
that calls to open can now return ENOMEM if needed. This allows the
caller to either be able to successfully open the file and read it, or
fail to open it in the first place.
Instead of specifying the boot argument to be root=/dev/hdXY, now
one can write root=PARTUUID= with the right UUID, and if the partition
is found, the kernel will boot from it.
This feature is mainly used with GUID partitions, and is considered to
be the most reliable way for the kernel to identify partitions.
The partitioning code was very outdated, and required a full refactor.
The new subsystem removes duplicated code and uses more AK containers.
The most important change is that all implementations of the
PartitionTable class conform to one interface, which made it possible
to remove unnecessary code in the EBRPartitionTable class.
Finding partitions is now done in the StorageManagement singleton,
instead of doing so in init.cpp.
Also, now we don't try to find partitions on demand - the kernel will
try to detect if a StorageDevice is partitioned, and if so, will check
what is the partition table, which could be MBR, GUID or EBR.
Then, it will create DiskPartitionMetadata object for each partition
that is available in the partition table. This object will be used
by the partition enumeration code to create a DiskPartition with the
correct minor number.
The StorageManagement class has 2 roles:
1. During boot, it should find all storage controllers in the machine,
and then determine what is the boot device.
2. Later on boot, it is a registrar of all storage controllers and
storage devices. Thus, it could be used to show information about these
devices when implemented.
This change allows the user to specify a boot driver other than /dev/hda
and if it's connected in the machine - it will boot.
