User`s manual

Special Topics
5-4 Single Board Computers SCSI Software UserÕs Manual
5
Example
This section shows, through example, how to enable debug logging, how to
record debug information in a trace entry, and how to display the log. A ROM
debugger will be used to initialize the sdt_tvalue structure and display the
log. The information which will be displayed is from currently embedded log
entry points in the Firmware.
Examples shown here use the MVME167 ROM debugger; however, these
same commands can be used with the other ROM debuggers.
User Level Setup
This section demonstrates a method for enabling debug logging by the
Firmware. The ROM debugger calls sdt_tinit() before its first access to a local
SCSI device after a board reset. Before this access is made, the sdt_tvalue
structure must be located and initialized. Use the ROM debugger to find and
initialize this structure which is located in NVRAM.
1. Find the address of the string
'PRVT' using the BS command.
167-Bug>bs fffc0000 fffc2000 'PRVT'
Effective address: FFFC0000
Effective address: FFFC2000
FFFC16F8
167-Bug>
String address = 0xFFFC16F8
2. The pointer to sdt_tvalue resides at 0xFFFC16F8 + 4. Display this pointer
value using the MD command.
167-Bug>md fffc16f8+4
FFFC16FC FFFC 1758 0000 0000 0014 0032 5350 4346 ...X.......2SPCF
167-Bug>
sdt_tvalue structure address = 0xFFFC1758
3. Initialize sdt_tvalue to the following values using the MM command.
Set the debug_flag to 0x00440000 at location 0xFFFC1758.
Set the begin address to 0x00400000 at location 0xFFFC175C.
Set the end address to 0x00800000 at location 0xFFFC1760.
167-Bug>mm fffc1758;l
FFFC1758 00000000? 00440000
FFFC175C 00000000? 00400000
FFFC1760 00000000? 00800000
FFFC1764 00092691? .
167-Bug>