DEC Digital Alpha VME 4/224 User Manual page 351

Description
Exercises one or more devices. As described in the preceding overview section,
the exer command uses two buffers, buffer1 and buffer2. The buffers are in main
memory in the memory zone heap.
Both buffer1 and buffer2 are initialized to a data pattern before any I/O
operations occur. These buffers are never reinitialized, even after completing
one or more passes.
The data patterns with which the buffers are initialized are 0x5A in every byte
of each buffer. Alternatively, you can specify the patterns by using the string
arguments to the data pattern options -d1 and -d2.
The -d1 and -d2 options use a postfix string argument to initialize a buffer's
contents. For each byte in the specified buffer, starting with the first byte, this
postfix string is passed to the eval command, which returns a byte value that is
then written to the specified buffer.
The following options specify the amount of device data to be processed:
-sb Starting block
-eb Ending block
-l Number of blocks
-bs Block size in bytes
-bc Number of blocks in a packet, where a packet is the amount of data
transferred in one I/O operation
You can specify reading, writing, comparing buffers, and other operations to occur
in various combinations and sequences. These operations are specified by a string
of 1-character command codes known as the ''action string.'' Specify the action
string as an argument to the action string option, -a.
Each command code character in the action string is processed in a sequence from
left to right. Each time that the exer command completes all of the operations
specified by the action string, the command reduces the remaining amount of
device data to be processed by the size of the last packet processed by the action
string. The exer command processes the action string repeatedly until the
specified amount of device data has been processed.
Lowercase action string characters rwn specify operations that involve buffer1.
Uppercase action string characters RWN specify operations that involve buffer2.
The action string character c involves both buffers. The action string characters
-? do not involve either buffer.
exer
Console Commands 13–43