Intel IXP400 manual Mapping to OS Native Buffer Types, VxWorks* Mblk Buffer

Intel® IXP400 Software

Buffer Management

Table 2. IX_MBUF Field Details (Sheet 2 of 2)

Field / MACRO	Purpose	Used by Access-Layer?
IX_OSAL_MBUF_FLAGS
Parameter type: IX_MBUF *	Buffer flags.	Yes, by some components.
Return type: unsigned char
Description: Returns the flags field of the
buffer
Reserved	Reserved field, used to preserve 32-	No.
	bit word alignment.
IX_OSAL_MBUF_NET_POOL
Parameter type: IX_MBUF *	32-bit pointer to the parent pool of	Yes, by some components.
Return type: unsigned int
	the buffer
Description: Returns a 32-bit pointer to the
parent pool of the buffer
IX_OSAL_MBUF_PKT_LEN
Parameter type: IX_MBUF *	Total length (octets) of the data	Yes, where buffer chaining is
Return type: unsigned int	sections of all buffers in a chain of
Description: Returns the length of the packet	buffers (packet). Typically set only in	supported.
	the first buffer in the chain (packet).
(typically stored in the first buffer of the
packet only)
Reserved	Used by VxWorks*	No.

3.6Mapping to OS Native Buffer Types

OSAL provides buffer-translation macros for users to translate OS-specific buffer formats to OSAL IXP buffer format and vice versa. The mapping of OS buffer fields to the IXP400 software buffer format is usually done in the OS specific driver component. However, for ease of users the OSAL component provides generic macros for VxWorks, and Linux operating system that does the translation. Depending upon the build, the OSAL component will translate the macros to its OS- specific implementation. The general syntax for using these macros is as follows:

•IX_OSAL_CONVERT_OSBUF_TO_IXPBUF(osBufPtr,ixpBufPtr)

•IX_OSAL_CONVERT_IXPBUF_TO_OS_BUF(ixpBufPtr,osBufPtr)

These macros are intended to replace Linux skbuf and VxWorks mbuf conversions. Users can also define their own conversion utilities in their package to translate their buffers to IXP buffers (IX_OSAL_MBUF).

3.6.1VxWorks* M_BLK Buffer

The first structure IX_MBUF of the IXP_BUF buffer format is compatible with VxWorks M_BLK structure. It is also intended to provide a backward compatibility to previous Intel® IXP400 Software release. For this reason, when compiled for VxWorks, the IX_MBUF buffer format is compatible directly as an M_BLK buffer. The Intel® IXP400 Software does not make use of all the fields defined by the M_BLK buffer. The macros listed in Table 3 are used by the IXP400 software to access the correct fields within the M_BLK structure.

The M_BLK structure is defined in the global VxWorks header file “netBufLib.h”.

April 2005	IXP400 Software Version 2.0	Programmer’s Guide
46	Document Number: 252539, Revision: 007