Trace Buffer Register (Tbreg); Tbreg Format - Intel XScale Core Developer's Manual

9.12.1.2

Trace Buffer Register (TBREG)

The trace buffer is read through TBREG, using MRC and MCR. Software should only read the
trace buffer when it is disabled. Reading the trace buffer while it is enabled, may cause
unpredictable behavior of the trace buffer. Writes to the trace buffer have unpredictable results.
Reading the trace buffer returns the oldest byte in the trace buffer in the least significant byte of
TBREG. The byte is either a message byte or one byte of the 32 bit address associated with an
indirect branch
Table 9-17.

TBREG Format

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
reset value: unpredictable
Bits
31:8 Read-as-Zero/Write-ignored
7:0 Read / Write-unpredictable
Developer's Manual
message.Table 9-17 shows the format of the trace buffer register.
Access
Reserved
Message Byte or Address Byte
January, 2004
Intel XScale® Core Developer's Manual
9 8 7 6
Description
Software Debug
5 4 3 2 1 0
Data
147