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Hermès Bélusca-Maïto
3a7fe56a5d
---- 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): https://github.com/reactos/reactos/blob/db419efbf26c78e39fb57bcaf4f9e4d915d0c96e/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.