Intel Extensible Firmware Interface - Manual (Page 519)

Protocols — PCI Bus Support
Version 1.10 12/01/02 12-101
Table 12-18. Recommended PCI Device Driver Layout (continued)
Offset Byte
Length
Value
Description
0x30 1 0x03 Code Type
0x31 1 XX Indicator. Bit 7 clear means another image follows. Bit 7 set means
that this image is the last image in the PCI Option ROM. Bits 0–6 are
reserved.
0x00
0x80 Additional images follow this image in the PCI Option ROM
This image is the last image in the PCI Option ROM
0x32 2 0x0000 Reserved
0x34 X XXXX The beginning of the PCI Device Driver's PE/COFF Image
12.4.3 Nonvolatile Storage
A PCI adapter may contain some form of nonvolatile storage. Since there are no standard access
mechanisms for nonvolatile storage on PCI adapters, the PCI I/O Protocol does not provide any
services for nonvolatile storage. However, a PCI Device Driver may choose to implement its own
access mechanisms. If there is a private channel between a PCI Controller and a nonvolatile
storage device, a PCI Device Driver can use it for configuration options or vital product data.
NOTE
The fields RomImage and RomSize in the PCI I/O Protocol do not provide direct access to the
PCI Option ROM on a PCI adapter. Instead, they provide access to a copy of the PCI Option ROM
in memory. If the contents of the
RomImage are modified, only the memory copy is updated. If a
vendor wishes to update the contents of a PCI Option ROM, they must provide their own utility or
driver to perform this task. There is no guarantee that the BAR for the PCI Option ROM is valid at
the time that the utility or driver may execute, so the utility or driver must provide the code
required to gain write access to the PCI Option ROM contents. The algorithm for gaining write
access to a PCI Option ROM is both platform specific and adapter specific, so it is outside the
scope of this document.