Specifications

Operating System Boot, Sleep, and Wake QSSC-S4R Technical Product Specification
210
19.1.3 Boot Order Table
The BIOS supports the Boot Order Table (BOT), which exposes the system boot order along with device priority
orders. In addition, the Boot Order table includes the device names and hardware path details in addition to the boot
priority order.
The Boot Order Table is located in IPMI System boot options OEM parameter 125. Note that this is a multi-block
parameter with the block size reported in OEM parameter 120. This block size defines the number of bytes of the BOT,
which may be stored in each block of OEM parameter 125.
19.1.3.1 BOT Organization
The BOT consists of three sections concatenated into a single data block as shown in the following table.
Table 137. Overall Boot Order Table (BOT) Structure
Boot
Order
Table
(BOT)
Offset Section Length Description
00h Header Fixed (11
bytes)
Length field indicates total size of Header, Order Tables
and Device Name(s).
See Section 19.1.3.2
0Bh Order Tables Variable See Section 19.1.3.3
0Bh +
length of
Order
Table(s)
Device
Name(s)
Variable See Section 19.1.3.4
19.1.3.2 BOT Header
The Header section is of fixed length, and at a fixed location (the start) in the BOT.
Table 138. Boot Order Table Header Structure
Header
Offset Name Length Description
00h
A
nchor String Four bytes Signature string “_BO_” identifying Boot Order Table (BOT).
The four ASCII character value is 5F 42 4F 5F.
04h BOT Checksum 1 Byte Byte value to obtain zero checksum of entire table.
05h BOT Major
Revision
1 Byte The major revision in BCD number. For this version of the
specification, the revision is 00h.
06h BOT Minor
Revision
1 Byte The minor revision in BCD number. For this version of the
specification, the revision is 95h.
07h Length 1 Word Length of the Boot Order table structure. Stored in little endian
byte order.
09h Reserved 1 Byte Reserved
0Ah Update flag 1 Byte Flag to indicate the Boot Order has been updated.
Bit 0 = 1 if BIOS has updated the Boot order
Bit 1 = 1 if management application has updated the Boot
order.
Other bits are reserved.
Both bits may be set at the same time; the BIOS update takes
priority.
A
ll other times, the BIOS retains the existing boot order.
19.1.3.3 BOT Order Tables
The Order Table section consists of n+1 tables, where n is the number of device classes present.
Table 139. BOT Order Table Structure
Order Table Description