The alternate status register is not part of the same set of registers
as all the other stuff.
Also rename wait_400ns() to io_delay() since we had no guarantee that
it was waiting for 400ns..
The complication is around /proc/sys/ variables, which were attached
to inodes. Now they're their own thing, and the corresponding inodes
are lazily created (as all other ProcFS inodes are) and simply refer
to them by index.
Our logic for using the ATA_CMD_CACHE_FLUSH functionality was a bit wrong,
and now it's better.
The ATA spec says these two things:
> The device shall enter the interrupt pending state when:
> 1) any command except a PIO data-in command reaches command completion
> successfully;
> ...
> The device shall exit the interrupt pending state when:
> 1) the device is selected, BSY is cleared to zero, and the Status
> register is read;
This means that our sequence of actions was probably never going to work.
We were waiting in a loop checking the status register until it left the
busy state, _then_ waiting for an interrupt. Unfortunately by checking the
status register, we were _clearing_ the interrupt we were about to wait
for.
Now we just wait for the interrupt - we don't poll the status register at
all. This also means that once we get our `wait_for_irq` method sorted out
we'll spend a bunch less CPU time waiting for things to complete.
Apparently we need to poll the drive for its status after each sector we
read if we're not doing DMA. Previously we only did it at the start,
which resulted in every sector after the first in a batch having 12 bytes
of garbage on the end. This manifested as silent read corruption.
It is now possible to mount ext2 `DiskDevice` devices under Serenity on
any folder in the root filesystem. Currently any user can do this with
any permissions. There's a fair amount of assumptions made here too,
that might not be too good, but can be worked on in the future. This is
a good start to allow more dynamic operation under the OS itself.
It is also currently impossible to unmount and such, and devices will
fail to mount in Linux as the FS 'needs to be cleaned'. I'll work on
getting `umount` done ASAP to rectify this (as well as working on less
assumption-making in the mount syscall. We don't want to just be able
to mount DiskDevices!). This could probably be fixed with some `-t`
flag or something similar.
The previous implementation of the PIIX3/4 PATA/IDE channel driver only
supported a single drive, as the object model was wrong (the channel
inherits the IRQ, not the disk drive itself). This fixes it by 'attaching'
two `PATADiskDevices` to a `PATAChannel`, which makes more sense.
The reading/writing code is presented as is, which violates the spec
outlined by Seagate in the linked datasheet. That spec is rather old,
so it might not be 100% up to date, though may cause issues on real
hardware, so until we can actually test it, this will suffice.
2019-07-28 15:44:01 +02:00
Renamed from Kernel/Devices/IDEDiskDevice.cpp (Browse further)
