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

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.

So my question is:

• Should we use ETM4D instead of ETMV4I?

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

• 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;

              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 } }

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

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