SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
Technically not supported by the original ATA specification, IDE
hot swapping is still in practice possible, so the only sane way
to start support it is with ref-counting the IDEChannel object so if we
remove a PATADiskDevice, it's not gone with it.
An article about IDE limits states that:
"Hard drives over 8.4 GB are supposed to report their geometry as
16383/16/63. This in effect means that the `geometry' is obsolete, and
the total disk size can no longer be computed from the geometry, but is
found in the LBA capacity field returned by the IDENTIFY command.
Hard drives over 137.4 GB are supposed to report an LBA capacity of
0xfffffff = 268435455 sectors (137438952960 bytes). Now the actual disk
size is found in the new 48-capacity field."
(https://tldp.org/HOWTO/Large-Disk-HOWTO-4.html) which is the main
reason to not support CHS as harddrives with less than 8.4 GB capacity
are completely obsolete.
Another good reason is that virtually any harddrive in the last 20 years
or so, supports LBA mode. Therefore, it's probably OK to just ignore CHS
as it's unlikely to encounter a harddrive that doesn't support LBA.
This is somewhat simplifying the IDE initialization and access code.
Also, we should use the ATAIdentifyBlock structure if possible,
so now we do it instead of using macros to calculate offsets.
With the usage of the ATAIdentifyBlock structure, we now use the
48-bit LBA max count if the drive indicates it supports 48-bit LBA mode.
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.
Besides removing the monolithic DevFSDeviceInode::determine_name()
method, being able to determine a device's name inside the /dev
hierarchy outside of DevFS has its uses.
This new subsystem is somewhat replacing the IDE disk code we had with a
new flexible design.
StorageDevice is a generic class that represent a generic storage
device. It is meant that specific storage hardware will override the
interface. StorageController is a generic class that represent
a storage controller that can be found in a machine.
The IDEController class governs two IDEChannels. An IDEChannel is
responsible to manage the master & slave devices of the channel,
therefore an IDEChannel is an IRQHandler.
2020-12-21 00:19:21 +01:00
Renamed from Kernel/Devices/PATADiskDevice.h (Browse further)
