RAM 6.0 BUX II Series Betriebsanweisung PDF herunterladen (Seite 118)

VxWorks

BSP Developer’s Guide, 6.0

110

Thus, the offset parameter is biased so that an offset of 0 points to the first byte of

the VxWorks boot line. This is always true even if the boot line is not at the

beginning of the non-volatile memory area.

All BSPs must define the following macros:

NV_RAM_SIZE

Defines the total bytes of NVRAM available. Define

NV_RAM_SIZE in

config.h, or bspname.h. For boards without NVRAM, define

NV_RAM_SIZE

NONE.

BOOT_LINE_SIZE

Defines the number of bytes of NVRAM that are reserved for the VxWorks

boot line. The default value is 255 and is defined in configAll.h.

BOOT_LINE_SIZE must be less than or equal to NV_RAM_SIZE. To override the

default value of

BOOT_LINE_SIZE, first undefine then define the macro in

config.h or bspname.h.

NV_BOOT_OFFSET

Defines the byte offset to the beginning of the VxWorks boot line in NVRAM.

The default value is 0 and is defined in configAll.h. This is distinct from

BOOT_LINE_OFFSET, the offset of the boot line stored in RAM.

The routines sysNvRamSet( ) and sysNvRamGet( ) have an offset parameter.

NV_BOOT_OFFSET is greater than zero, you can access the bytes before the

boot line by specifying a negative offset. To override the default value of

NV_BOOT_OFFSET, first undefine then define the macro.

For boards without NVRAM, include the file

target/src/drv/mem/nullNvRam.c for stubbed out versions of the routines that

return

ERROR.

Scaling RAM Size

In order to configure the heap, VxWorks must know how much RAM is available

on the system. This information is provided by the sysMemTop( ) BSP routine. As

mentioned earlier, your initial BSP design should use a version of sysMemTop( )

in which memory size is configured at compile time. However, for many systems,

it is appropriate to rewrite sysMemTop( ) so that it probes actual hardware to

determine how much memory is physically present on the system. The actual

modifications to the sysMemTop( ) routine can sometimes be made as part of the

memory controller driver. For more information about this process, see the

memory driver section of the VxWorks Device Driver Developer’s Guide: Additional

Drivers.

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