Changes between Version 5 and Version 6 of Developer/FileSystems


Ignore:
Timestamp:
Jan 7, 2008, 11:46:03 AM (12 years ago)
Author:
ChrisJohns
Comment:

Add block device details.

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  • Developer/FileSystems

    v5 v6  
    8282# Flash Disk
    8383# Non-volatile Disk
     84
     85The ATA Disk Drive support allows an IDE type device to be accessed. The device normally has a Master Boot Record and a partition table. The ATA Disk driver is currently located in libchip. The IDE disk can be a hard disk or a Compact Flash disk in IDE mode.
     86
     87The RAM disk allows a fixed sized disk driver to be created in RAM. You can provide the address of the RAM or let the driver allocate the RAM from the heap. If you create a disk from the heap you will need to format it. If you provide the address of the RAM to use it could reside in static RAM and therefore survive a reset. If the RAM is battery backed up then you may consider the Non-volatile or NVDISK driver.
     88
     89The Flash disk driver or FDISK driver maps a block disk device to flash devices. You can specify the devices and how much of each device to use when creating a disk. The driver will manage the flash sectors/segments and handle the mapping of the disk blocks to the flash devices. The types of flash supported is independent of the flash driver. You define desvice descriptions the flash driver uses. The flash driver is not a flash file system, rather it is a way to map an existing block device file system to flash devices. Currently the flash driver does not support NOR flash devices and does not journal blocks written to the disk. This means you need to manage power failures. Journaling support could be added in the future and if you are interested in supporting this happening please contact OAR Corp.
     90
     91The Non-volatile or NVDISK is between the RAM disk and the Flash disk. It provides a one to one mapping of blocks to the device like the RAM disk but it also adds a CRC checksum on each block. The NVDISK drive is suitable for battery backed up static RAM or EEPROM type devices that are byte re-programmable.