----
Thanks to the following testers!
- Dmitry Borisov (@disean) for testing on NEC PC-98 emulator;
- Justin Miller (@DarkFire01) for testing on UEFI platform;
- Stanislav Motylkov (@binarymaster) for testing on Xbox emulator
(xemu), both livecd and bootcd.
----
"SectorsPerTrack" is for the legacy Cylinders/Heads/Sectors(PerTrack)
scheme.
- On BIOS-based PCs, INT 13h can return (for LBA-only drives) an invalid
geometry, like: C/H/S = (-1)/(-1)/(-1). This is also what happens in
our hwide.c driver (see IdentifyDevice() for ATAPI devices):
db419efbf2/boot/freeldr/freeldr/arch/drivers/hwide.c (L918-L928)
as well as on VirtualBox for CD-ROMs:
https://www.virtualbox.org/browser/vbox/trunk/src/VBox/Devices/PC/BIOS/disk.c#L155
- Therefore, we cannot reliably calculate a valid total number of sectors
by multiplying the Cylinders*Heads*SectorsPerTrack values. In addition,
such a multiplication could overflow a 32-bit ULONG.
Thus, a separate ULONGLONG Sectors member is required to hold such a
value, that is retrieved differently. For example for ATAPI devices,
our hwide.c driver does return a valid TotalSectors value, even though
CHS values are invalid. Other platforms, like UEFI, just work using
logical block addressing (LBA) values (see EFI_BLOCK_IO_MEDIA).
- uefidisk.c : Per the spec, EFI_BLOCK_IO_MEDIA::LastBlock contains
"The last LBA on the device. [...] For ATA devices, this is reported
in IDENTIFY DEVICE data words 60-61 (i.e., Total number of user
addressable logical sectors) _minus one_.
For SCSI devices, this is reported in the READ CAPACITY parameter
data 'Returned Logical Block Address field' _minus one_."
In other words, LastBlock is a zero-based LBA index quantity. The
corresponding total number of valid "sectors"/blocks of the device
is therefore, (LastBlock + 1).
- Cleanup some old disabled code.
3a7fe56a5d