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Segmentation Fault

Former Member


Hi,

I made a simple register on the PL that I can read and write to using a simple bare metal application.  When I try to do the same on a compiled linux app I get a segmentation fault.  Do I need to modify something on the linux side to get this to work?  The device tree?  Thanks!


Here is what I am doing...

int *reg0 = REGISTERS_BASE_ADDRESS;

// Read Reg0
printf("Reg0 is r
", *reg0);

// Write Reg0
*reg0 = 1;

// Read Reg0
printf("Reg0 is now r
", *reg0);

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  • 0

    Hello xspyder,

    I think that the address space of the device belongs to kernel address space, for these reason you're not allowed to manage those addresses (I guess).
    Searching the net it seems that you have to use "mmap" to map the address space of the device into user space, then you can use pointers like you're trying to do. Could you try this. Let me know if worked :)

    I'd like to do the same think, but I can't work with the zedboard these days. For this reason I use qemu to run my simple programs. One of them uses mmap with address 0x30000000 (belonging to DDR) and it seems that it's all right. So, try to use this trick considering the device starting address instead of 0x30000000.

    Bye,

    sticken

Reply
  • 0

    Hello xspyder,

    I think that the address space of the device belongs to kernel address space, for these reason you're not allowed to manage those addresses (I guess).
    Searching the net it seems that you have to use "mmap" to map the address space of the device into user space, then you can use pointers like you're trying to do. Could you try this. Let me know if worked :)

    I'd like to do the same think, but I can't work with the zedboard these days. For this reason I use qemu to run my simple programs. One of them uses mmap with address 0x30000000 (belonging to DDR) and it seems that it's all right. So, try to use this trick considering the device starting address instead of 0x30000000.

    Bye,

    sticken

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