Hi,

On Tue, 29 Jun 2021 at 07:10, Jinnan Li A <jinnan.a.li@ericsson.com> wrote:

Hi Linaro Coresight Team,

We are debugging Arm ETB. We don’t know how to dump the ETB data with the right method. Please give me some comments, thanks so much.

Let’s me give a description for our ETB environment first.

For the Core-sight components, after enabled ETM and ETB. We can dump the ETB data after a while.

According to ARM_CoreSight_Architecture_Specification.pdf, then We think it works by changing the trace source ID.

The following data is from the head of trace buffer.

Before the trace source ID = 2:

00000005 = 00 | 0b10<<1+0b1 | 0x0 | 0x0

After the trace source ID = 4:

00000009 = 00 | 0b100<<1+0b1 | 0x0 | 0x0

0000000B

00000000

04000000

00800000

This doesn't match the file you attached. (tracebuffer.bin)

1st 16 bytes are 00 00 09 00 00 00 0b 00 00 00 00 00 00 04 00 00

The registers about ETM are as follows.

TRCCONFIGR(id:0x10)=0x31F07

TRCTRACEIDR(id:0x40)=0x2

TRCIDR8(id:0x180)=0x1

TRCIDR9(id:0x184)=0x20

TRCIDR10(id:0x188)=0x2

TRCIDR11(id:0x18c)=0x0

TRCIDR12(id:0x190)=0x1

TRCIDR13(id:0x194)=0x0

TRCIDR0(id:0x1e0)=0x8020EFF

TRCIDR1(id:0x1e4)=0x4100F401 ARM ETM4.0.1

TRCIDR2(id:0x1e8)=0x420004

How to use OpenCSD for M7?

We also try to dump with your source code “OpenCSD” https://github.com/Linaro/OpenCSD, it’s a useful tool. But maybe we lost some configuration, our ETB can’t be dumped.

Trace Packet Lister : Protocol printer ETMV4I on Trace ID 0x0

Idx:0; ID:0; I_NOT_SYNC : I Stream not synchronised

Idx:285; ID:0; I_INCOMPLETE_EOT : Incomplete packet at end of trace.[I_NOT_SYNC]

ID:0 END OF TRACE DATA

Trace Packet Lister : Trace buffer done, processed 288 bytes.

The attachments are the settings and trace buffer.

The trc_pkt_decoder requires a snapshot in the format defined in the docs supplied with the opencsd project. The traceinfo.ini file you provide is not valid.;

So my question is:

Should we use ETM4D instead of ETMV4I?

#define OCSD_BUILTIN_DCD_ETMV4D "ETMV4D" /**< ETMv4 data decoder */

ETMv4 uses separate streams for ETM instruction and data trace. The ID of the data trace is ID of Instruction trace +1.

You would need to enable two decoders, one for instruction trace, one for data trace. However, the OpenCSD development has not yet implemented the decoder for data trace.

Does OpenCSD support ETMV4D and Cortex-M7?

We can see the TODO from git repo.

Support to be added: ETMv4 data trace - packet processing and decode.

const char *decoderName = bDataChannel ? OCSD_BUILTIN_DCD_ETMV4D : OCSD_BUILTIN_DCD_ETMV4I;

The data decoder for ETM v4 has not been implemented. You can decode instriuction trace from ETMv4 / M class core..

              I didn’t see the M7 support.

    69      { "Cortex-M0", { ARCH_V7, profile_CortexM } },

    70      { "Cortex-M0+", { ARCH_V7, profile_CortexM } },

    71      { "Cortex-M3", { ARCH_V7, profile_CortexM } },

    72      { "Cortex-M4", { ARCH_V7, profile_CortexM } }

This support associates core types from the snapshot with architecture and profile types. If the one you want is not there, add it, or use one that is and has the same profile and architecture version.

A stupid question, could you kindly tell me which ARM document introduce the data encoder?

I do not understand what you mean by "data encoder"? The ETMv4 specification contains all the information on trace formats.

I debug test code step by step(see below lines), but it doesn’t match with ETB trace buffer. I am not sure if there has more document about PEencoder/decoder.

   debug_count += 1;

4B11                ldr     r3,0x604

681B                ldr     r3,[r3]

3301                adds    r3,#0x1

4A0F                ldr     r2,0x604

6013                str     r3,[r2]

Looking forward to your feedback.

Thank you so much.

BR//Jinnan

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Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK