= GIET-VM / RDK Driver = 

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The [source:soft/giet_vm/giet_drivers/rdk_driver.c rdk_driver.c] and [source:soft/giet_vm/giet_drivers/rdk_driver.h rdk_driver.h] files define the RDK driver. 

This driver supports a virtual disk implemented as a memory segment, in the physical address space. This ramdisk vseg must be defined in the mapping.

This driver is called by the generic IOC driver, when the USE_IOC_RDK flag is set in the hard_config.h file.

The _rdk_read() and _rdk_write() blocking functions use a software memcpy, whatever the selected mode (BOOT / KERNEL / USER). 
These blocking functions return only when the transfer is completed.
As the number of concurrent accesses is not bounded, these functions don't use the _ioc_lock variable.

The SEG_RDK_BASE virtual address must be defined in the hard_config.h file when the USE_IOC_RDK flag is set.

#ifndef _GIET_RDK_DRIVERS_H_
#define _GIET_RDK_DRIVERS_H_

 === unsigned int '''_rdk_init()''' ===
This function does nothing, but is required by the generic IOC API.

 === unsigned int '''_rdk_read'''( unsigned int lba,   unsigned int buffer,  unsigned int count ) ===
This function transfer data from the RAMDISK to a memory buffer. 
 * mode     : BOOT / KERNEL / USER (unused)
 * lba      : first block index on the block device
 * buffer   : virtual base address of the memory buffer
 * count    : number of blocks to be transfered.
Returns 0 if success, > 0 if error.

 === unsigned int '''_rdk_write'''( unsigned int lba,   unsigned int buffer,  unsigned int count ) ===
This function transfer data from a memory buffer to the RAMDISK. 
 * mode     : BOOT / KERNEL / USER (unused)
 * lba      : first block index on the block device
 * buffer   : virtual base address of the memory buffer
 * count    : number of blocks to be transfered.
Returns 0 if success, > 0 if error.

 === unsigned int '''_rdk_get_block_size'''() ===
This function returns the block size.

 === unsigned int '''_rdk_get_status'''() ===
This function returns always 0, but is required bi the generic IOC API.