TMS320F28P650DK: Example linker syntax for “run-from-RAM, load-from-flash” at the object-file level

Srinivasan Venkatasubramani

Part Number: TMS320F28P650DK
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hi,

To reduce ISR utilization and improve performance, I am trying to move code to executing from RAM instead of FLASH.

Rather than tagging every function with #pragma CODE_SECTION(fn, ".TI.ramfunc") , I’d like to relocate entire object files to execute from RAM LS8 during link step.

Can you point me to a C28x example snippet, CCS example project or the recommended linker syntax for "run from RAM, load from flash, at an object file level instead of function level?

I came across the "GROUP" command in this document, (software-dl.ti.com/ccs/esd/documents/sdto_cgt_Linker-Command-File-Primer.html#group-output-sections-together), and this is what I have so far,

GROUP

LOAD = APPFLASH_CPU1

RUN = RAMLS8

PAGE = 0

ALIGN(4)

LOAD_START(CtrlLoadStart)

LOAD_SIZE (CtrlLoadSize)

RUN_START (CtrlRunStart)

RUN_END (CtrlRunEnd)

{

state_voltage_match.obj (.text, .switch)

fault_monitor.obj (.text)

converter_control.obj (.text)

}

Is this the right way to go about this? Please let me know if you are able to help me with this.

11 months ago

0 Sudeshna Chaudhuri 11 months ago

TI__Intellectual 880 points

Hi Srinivasan Venkatas,

You may find an example named "flash_ex3_flash_to_ram" inside driverlib/f2838x/examples/c28x/flash/ folder which demonstrates a similar thing. You may use this as your reference.
When you open its sysconfig file from the sysconfig gui, you'll find a device_cmd.cmd file on the right side. Please check the encircled section.

Let me know if you need any further clarification.

0 Srinivasan Venkatasubramani 11 months ago in reply to Sudeshna Chaudhuri

Prodigy 80 points

Hi, thanks for taking the time to help me. The above example doesn't quite go over how I could link specific .obj files. Would you happen to know if there is an example that links specific .obj files to ramfuncs? And what the syntax would be to do it?

0 Sudeshna Chaudhuri 11 months ago in reply to Srinivasan Venkatasubramani

TI__Intellectual 880 points

Hi Srinivasan,

Does this help? e2e.ti.com/.../placing-obj-files-in-specific-segments

0 George Mock 11 months ago in reply to Sudeshna Chaudhuri

TI__Guru**** 253410 points

I apologize for the delay.

You can solve this problem ...

Srinivasan Venkatasubramani said:
To reduce ISR utilization and improve performance, I am trying to move code to executing from RAM instead of FLASH.

... with no changes to the linker command file. In the second post, Sudeshna shows a screenshot of a linker command file named device_cmd.cmd. It has a specification for an output section named .TI.ramfunc. This is exactly what you need. You don't need GROUP, or anything else you show in your first post.

If you want all of the functions in one file to load in flash and run from ram, build that file with the option --ramfunc=on. For the details on that option, please search the C28x compiler manual for the term ramfunc. It does not make sense to build all of the files with this option. I think you build with CCS version 20.x.x or later. In that case, to change the build options for just one file, right click on the file and choose Properties.

Thanks and regards,

-George

0 Srinivasan Venkatasubramani 11 months ago in reply to George Mock

Prodigy 80 points

I don't use CCS for build, using Cmake and docker environment on Visual Studio Code. I will need to work out how i can build a file with this option --ramfunc=on, my setup maybe its something I need to specify as part of my cmakefile, where i make a library for all the relavant files, that i want to run from RAM.

0 George Mock 11 months ago in reply to Srinivasan Venkatasubramani

TI__Guru**** 253410 points

Srinivasan Venkatasubramani said:
I will need to work out how i can build a file with this option --ramfunc=on, my setup maybe its something I need to specify as part of my cmakefile

This is the best way to go. But if you can't get it to work, there are other methods. Feel free to ask me about them.

Thanks and regards,

-George

0 Chris Yorkey 11 months ago in reply to George Mock

TI__Genius 16370 points

Thank you George and Srini for talking this through.

Srini please do reply back on this thread as you need to (if already, please don't hesitate).

We will keep this open for now.

TY,
Chris

0 Chris Yorkey 10 months ago in reply to Chris Yorkey

TI__Genius 16370 points

Srini,

We'd like to go ahead and close this ticket out if that's OK.

Unless you have more to add to the thread at this time?

Otherwise, we can create a new ticket and/or address offline.

Please let us know today if you can.

Thank you,
Chris

0 Chris Yorkey 10 months ago in reply to Chris Yorkey

TI__Genius 16370 points

Srini & All,

Closing this thread now. Let's discuss any further actions/questions offline.

Regards,
Chris

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TMS320F28P650DK: Example linker syntax for “run-from-RAM, load-from-flash” at the object-file level