This replaces the current disk detection and disk access code with
code based on https://wiki.osdev.org/IDE
This allows the system to boot on VirtualBox with serial debugging
enabled and VMWare Player.
I believe there were several issues with the current code:
- It didn't utilise the last 8 bits of the LBA in 24-bit mode.
- {read,write}_sectors_with_dma was not setting the obsolete bits,
which according to OSdev wiki aren't used but should be set.
- The PIO and DMA methods were using slightly different copy
and pasted access code, which is now put into a single
function called "ata_access"
- PIO mode doesn't work. This doesn't fix that and should
be looked into in the future.
- The detection code was not checking for ATA/ATAPI.
- The detection code accidentally had cyls/heads/spt as 8-bit,
when they're 16-bit.
- The capabilities of the device were not considered. This is now
brought in and is currently used to check if the device supports
LBA. If not, use CHS.
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