If the user requests to force PIO mode, we just create IDEChannel
objects which are capable of sending PIO commands only.
However, if the user doesn't force PIO mode, we create BMIDEChannel
objects, which are sending DMA commands.
This change is somewhat simplifying the code, so each class is
supporting its type of operation - PIO or DMA. The PATADiskDevice
should not care if DMA is enabled or not.
Later on, we could write an IDEChannel class for UDMA modes,
that are available and documented on Intel specifications for their IDE
controllers.
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 This in effect means that the `geometry' is obsolete, and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 reverts commit cfc2f33dcb.
We can't actually change the IRQ line value and expect the device
to work with it (this was my mistake).
That register is R/W so the firmware can figure out IRQ routing and put
the correct value and write it to the Interrupt line register.
As a compromise, if the fimrware decided to set the IRQ line to be 7,
or something else we can't deal with, the user can simply force the code
to work with IRQ 11, with the boot argument "force_ahci_irq_11" being
set to "on".
Instead of polling if the device ended the operation, we can just use
interrupts for signalling about end of IO operation.
In similar way, we use interrupts during device detection.
Also, we use the new Work Queue mechanism introduced by @tomuta to allow
better performance and stability :)
We can't use deferred functions for anything that may require preemption,
such as copying from/to user or accessing the disk. For those purposes
we should use a work queue, which is essentially a kernel thread that
may be preempted or blocked.
Alot of code is shared between i386/i686/x86 and x86_64
and a lot probably will be used for compatability modes.
So we start by moving the headers into one Directory.
We will probalby be able to move some cpp files aswell.
We previously ignored these values in the return value of
load_elf_object, which causes us to not allocate a TLS region for
statically-linked programs.
These errors are classed as fatal, so we need to recover from them.
Found while trying to debug AHCI boot on VMware Player,
where I got TFES.
From the spec: "Fatal errors (signified by the setting of PxIS.HBFS,
PxIS.HBDS, PxIS.IFS, or PxIS.TFES) will cause the HBA to enter
the ERR:Fatal state"
We were already recovering from IFS.
In case multiple file descriptors in the `fd_set` were already readable
and/or writable when calling Thread::block<SelectBlocker>(), we would
only mark the first fd in the output sets instead of all relevant fd's.
The short-circuit code path when blocking isn't necessary must ensure
that unblock flags are collected for all file descriptors, not just the
first one encountered.
Fixes#5795.
If we happen to read with offset that is after the end of file of a
device, return 0 to indicate EOF. If we return a negative value,
userspace will think that something bad happened when it's really not
the case.
