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Editorial Team
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Asked: 2026-05-21T17:05:06+00:00

I was asked this question in an interview. You are writing a PCI driver

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I was asked this question in an interview. You are writing a PCI driver and you want to export the hardware-related information to the /proc filesystem. The interesting thing is that I searched the driver code and I couldn’t find any call related to /proc filesystem though actually the information is exported. Is it done automatically? What is the mechanism? Can anyone please explain?

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1 Answer

  1. Editorial Team

    One way to do it is for your driver to

    • implement a function that will get called whenever a process reads the corresponding /proc entry with the following signature:

      int (*read_proc)(char *page, char **start, off_t offset, int count, int *eof, void *data);

    • register your function by passing its pointer to create_proc_read_entry(), which accepts the name of the /proc entry as a string among other things:

      create_proc_read_entry(“foobar”, 0, NULL, your_read_func_ptr, NULL);

    When your driver unloads, it should remove the entry with remove_proc_entry()

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