hw-glue-probe-bus (libglue.la :: glue_component_library)

Synopsis:

This component samples and/or traces bus traffic.

Functionality:

Modelling:

This component resembles a probe that transparently monitors bus traffic.

Behaviors
bus traffic passthrough
When the downstream accessor is configured, all incoming bus API calls to the upstream bus are passed through verbatim. Without the downstream accessor configured, the upstream bus will return bus::unmapped for all calls. Still, the sampling and tracing functions are still active.
bus traffic sampling

Every now and then (at an interval configured by the sample-interval attribute), a transaction is also reported via a collection of output pins. In sequence, the following output pins are driven:

"address" - address parameter
"data-high" - top 32 bits of bus data being read/written
"data-low" - bottom 32 bits of same
"status" - bus::status value returned from downstream
"type" - an encoded value identifying the size, endianness, and direction of the data transfer. Specifically, in C lingo, (type & 0x00F): log2 of access size (0/1/2/3 for *_int_1/2/4/8) (type & 0x010): 0x10 (little-endian) or 0x00 (big-endian) (type & 0x100): 0x100 (read) or 0x00 (write)

This sampling function is disabled if sample-interval is zero. The read-only interval-counter attribute indicates the current value of the modular transaction counter.

bus traffic tracing

If the trace? attribute is set, sampled bus traffic is traced to stdout in a compact format. The sampling counter is shared with the traffic probing behavior above.

One line per transaction is shown in a format resembling the common gdb simulators' --trace-core output:
[LABEL:] MODE:ADDRESS ARROW DATA [LATENCY] [STATUS] where LABEL is an optional label identifying the probe component. MODE is an encoding of the access type: zzz where le and be represent little- or big-endianness, and 1-8 represent the number of bytes transferred. ARROW is a redundant encoding of direction: {->,<-} for {read,write} ADDRESS and DATA are hex-encoded host-endian values, LATENCY is a string encoding of the bus access latency, though 0 is ommited STATUS is a string encoding of the bus::status, though ok is omitted Examples: write-be-2:0xa002001c <- 0x3442 read-le-8:0x807fff30 -> 0xffffffff807fff68 l:10 write-be-4:0xfeedface <- 0xdeadbeef unmapped!

Behaviors
bus traffic passthrough	When the `downstream` accessor is configured, all incoming bus API calls to the `upstream` bus are passed through verbatim. Without the `downstream` accessor configured, the `upstream` bus will return bus::unmapped for all calls. Still, the sampling and tracing functions are still active.
bus traffic sampling	Every now and then (at an interval configured by the `sample-interval` attribute), a transaction is also reported via a collection of output pins. In sequence, the following output pins are driven: "`address`" - address parameter "`data-high`" - top 32 bits of bus data being read/written "`data-low`" - bottom 32 bits of same "`status`" - bus::status value returned from downstream "`type`" - an encoded value identifying the size, endianness, and direction of the data transfer. Specifically, in C lingo, `(type & 0x00F): log2 of access size (0/1/2/3 for *_int_1/2/4/8) (type & 0x010): 0x10 (little-endian) or 0x00 (big-endian) (type & 0x100): 0x100 (read) or 0x00 (write)` This sampling function is disabled if `sample-interval` is zero. The read-only `interval-counter` attribute indicates the current value of the modular transaction counter.
bus traffic tracing	If the `trace?` attribute is set, sampled bus traffic is traced to stdout in a compact format. The sampling counter is shared with the traffic probing behavior above. One line per transaction is shown in a format resembling the common gdb simulators' `--trace-core` output: `[LABEL:] MODE:ADDRESS ARROW DATA [LATENCY] [STATUS]` where `LABEL` is an optional label identifying the probe component. `MODE` is an encoding of the access type: `zzz` where `le` and `be` represent little- or big-endianness, and 1-8 represent the number of bytes transferred. `ARROW` is a redundant encoding of direction: `{->,<-}` for `{read,write}` `ADDRESS` and `DATA` are hex-encoded host-endian values, `LATENCY` is a string encoding of the bus access latency, though 0 is ommited `STATUS` is a string encoding of the bus::status, though `ok` is omitted Examples: `write-be-2:0xa002001c <- 0x3442 read-le-8:0x807fff30 -> 0xffffffff807fff68 l:10 write-be-4:0xfeedface <- 0xdeadbeef unmapped!`

SID Conventions
functional supported
This is a functional component.
state save/restore not supported
This component does not support state save/restore.
watchpoints not supported
This component does not support watchpoints.
Reentrancy Control not supported
Reentrancy is not controlled.
presentation supported
This component presents attributes in the "pin", "setting", and "register" categories.

SID Conventions
functional	supported	This is a functional component.
state save/restore	not supported	This component does not support state save/restore.
watchpoints	not supported	This component does not support watchpoints.
Reentrancy Control	not supported	Reentrancy is not controlled.
presentation	supported	This component presents attributes in the "pin", "setting", and "register" categories.

Environment:

Related components

This component may be interjected between bus masters and a mapper to trace traffic.

new hw-glue-probe-bus bus-prober new SOME_KIND_OF_CPU cpu new SOME_KIND_OF_MAPPER mapper connect-bus cpu insn-memory bus-prober upstream connect-bus bus-prober downstream mapper access-port set bus-prober trace? 1

A statistics-gathering component could attach to the sampling output pins to maintain a picture of a program's memory access patterns.

Component Reference:

Component: hw-glue-probe-bus

pins
name direction legalvalues behaviors
address out any bus traffic sampling
data-high out any bus traffic sampling
data-low out any bus traffic sampling
status out bus::status values bus traffic sampling
type out enum values bus traffic sampling

pins
name	direction	legalvalues	behaviors
address	out	any	bus traffic sampling
data-high	out	any	bus traffic sampling
data-low	out	any	bus traffic sampling
status	out	bus::status values	bus traffic sampling
type	out	enum values	bus traffic sampling

buses
name addresses accesses behaviors
upstream unrestricted unrestricted bus traffic passthrough/etc.

buses
name	addresses	accesses	behaviors
upstream	unrestricted	unrestricted	bus traffic passthrough/etc.

attributes
name category legal values default value behaviors
trace? setting boolean 0 bus traffic tracing
sample-interval setting numeric 1 bus traffic sampling
interval-counter register numeric - bus traffic sampling
address pin numeric - bus traffic sampling
data-high pin numeric - bus traffic sampling
data-low pin numeric - bus traffic sampling
status pin numeric - bus traffic sampling
type pin numeric - bus traffic sampling
label setting any string - bus traffic sampling

attributes
name	category	legal values	default value	behaviors
trace?	setting	boolean	0	bus traffic tracing
sample-interval	setting	numeric	1	bus traffic sampling
interval-counter	register	numeric	-	bus traffic sampling
address	pin	numeric	-	bus traffic sampling
data-high	pin	numeric	-	bus traffic sampling
data-low	pin	numeric	-	bus traffic sampling
status	pin	numeric	-	bus traffic sampling
type	pin	numeric	-	bus traffic sampling
label	setting	any string	-	bus traffic sampling

accessors
name accesses behaviors
downstream unrestricted bus traffic passthrough