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ELAN 8X10

PM3350 ELAN 8 X10

DATA SHEET

PMC-970109

ISSUE 3

8 PORT ETHERNET SWITCH

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND PMC-SIERRA, INC. CUSTOMERS ONLY

The ELAN 8x10 expects to find executable firmware code within the boot image that will

perform the actual initialization process. However, the boot image is only 8 bits wide,

and thus the firmware code supplied within it cannot be directly executed by the ELAN

8x10 Switch Processor, which uses 32-bit instructions located on 32-bit boundaries. It is

thus necessary for the ELAN 8x10 to copy the boot image to a block of RAM that is set

aside for the purpose, and to convert the 8-bit boot image to a 32-bit version so that the

boot firmware code can be directly executed.

When a proper boot image signature is found, therefore, the ELAN 8x10 will

automatically go on to read a preformatted header within the boot image. This header

should supply information required to copy the boot image to a pre-allocated block of

RAM, and is formatted as follows:

Field

Size,

Bytes

Byte Offsets

from Start

Mnemonic

Description

+16

HDRFLAGS

Boot image processing flags

+20,+24,+28

CPYTARGET

Target RAM block to copy 8-bit boot

image to

+32,+36

CPYSIZE

Amount of data to copy in 64-byte

blocks

+40,+44,+48

CPYFROM

Source of copy data within boot image

+52,+56,+60

BOOTSTART

Starting address of bootstrap firmware

in target RAM block (valid after copy

completed)

+64,+68,+72,+76

CHECKSUM

32-bit checksum, computed over entire

boot image (including checksum field)

+80,+84,+88,+92

SPACER

Must be set to 0x00000000

hexadecimal

The HDRFLAGS field supplies some control bits that determine how the ELAN 8x10 will

handle the boot image, and is formatted as follows:

EightBit

CpyInt

JmpInt

reserved

EightBit:

If set, indicates that the boot image is formatted as an eight-bit-wide memory

block (following the general format that has already been presented);

otherwise, indicates a 32-bit boot image in a special format. This bit is

intended for factory use only, and should always be set by the customer.

CpyInt:

If this bit is set, the contents of the boot image should be copied to the

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