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PnE GDB debug launch slow, apparently dependent on size of .data segment

Question asked by troybeauparlant on Dec 28, 2016
Latest reply on Jan 2, 2017 by ZhangJennie

Hello All,


To summarize, I am having issues with a PnE GDB debug session taking an unreasonable amount of time to launch which appears to be dependent on the size of my .data segment.


My details are I am using KDS 3.0 and KDSK 1.3. I have a custom board with a K64F family of processor that uses the flexbus to connect some external SDRAM. In my linker file I defined a new memory segment m_flexbusram.

m_flexbusram      (RW)   : ORIGIN = 0x60000000, LENGTH = 0x04000000

in my project I define a number of data buffers in the new region so they will be located on my SDRAM. In the format:

unsigned short BUFFER[SIZE] __attribute__ ((section(".flexbusram")));

This is when I first encountered my project freezing at 98% when I tried to launch a debug session. I believed it was truly frozen until I tried shrinking the size of all my buffers located on SDRAM. Experimenting, I found that the speed at which my  debug session launched was linearly related to the size of my buffers. While small, a project build reported my build size to be

text         data      bss         dec

206796   24408   117708   348912

at this size the debug session launches in seconds. Switching to use the desired sizes for my buffers, the build reports

text         data            bss         dec

206828   40804680   117708   41129216

and at this size the session requires about 90 minutes to launch.

Changing the buffer sizes between these two extremes results in linearly relative sizes of my .data segment and relative launch times for my debug session.


Once embedded on my board the software boots and runs just fine on power up, its the debug sessions which take lengthy amounts of time to launch. I'm trying to better understand what the GDB server is doing with my initialized data that it dislikes but I so far haven't made progress with my search results. I can include other pieces of the linker file I edited to create the new flexbusram region if anyone believes it is relevant but I wanted to avoid clutter above.


Any feedback or advice is of course appreciated!