topic Re: Linkscripts and how to put all data from a specific object file into a specific part of memory in MCUXpresso IDE

Linkscripts and how to put all data from a specific object file into a specific part of memory

nxp16 — Thu, 22 Oct 2020 21:29:46 GMT

Hi,

I have at least two object files whose data (.data and .bss) needs to go into SRAM_DTC, and not just their globals. I have an app that uses USDHC. If I build a version of this app with all data put in SRAM_DTC by default (using C/C++ Build >Settings > Linker > Managed Linker Script settings), it works perfectly. However, if I build a version that puts all data into SRAM_OC by default, it doesn't work at all. I think it's due to some things being accessed via DMA that need to be in DTC. I know I can use __attribute__ section tags inside my code, but this is not helping. I need to be able to be able to tell the linker to put an entire .o file of .data/.bss into DTC using a linker file (unless there is another way). I tried this using the flexspi nor example as a base and modifying it thusly:

linkscripts/bss.ldt:

<#if memory.name=="SRAM_DTC">
*esp_sdio.o(.bss*)
*esp_slave.o(.bss*)
</#if>

data.ldt:

<#if memory.name=="SRAM_DTC">
*esp_sdio.o(.data*)
*esp_slave.o(.data*)
</#if>

main_bss.ldt:

*(EXCLUDE_FILE(*esp_sdio.o *esp_slave.o) .bss*)

main_data.ldt:

*(EXCLUDE_FILE(*esp_sdio.o *esp_slave.o) .data*)

But unfortunately, this causes problems with any other data where I've specifically used __attribute__ section to put things into DTC (they end up in OC instead!) in other object modules.

Can anyone help me with this?

Thanks!

Re: Linkscripts and how to put all data from a specific object file into a specific part of memory

nxp16 — Thu, 22 Oct 2020 22:17:03 GMT

It turns out, that it's not just my code. The sdmmc drivers provided with the sdk do NOT work at all if you default global data placement to SRAM_OC (which I have to do because my full app uses too much ram for DTC). I was somewhat able to get this working by adding sections to the link settings but not fully yet:

I will update here when I've figured it out fully. I wonder if the same problem happens using SDRAM as the default?

Re: Linkscripts and how to put all data from a specific object file into a specific part of memory

nxp16 — Fri, 23 Oct 2020 13:48:26 GMT

I also had to add fsl_usdhc.o to the list. Now I just have problems in my own code (well, ESP32's code). Some of this code uses "buffers" on the stack/heap (uint32_ts and such). I just have to figure out a good way to make those end up in DTC (because the stack/heap is in OC by default).