Question:

Is it possible to overload memory mapped file loader? In case of page fault, Linux kernel would not load the requested data from disk, but instead of it, user-defined function would be called, which would fill the memory page.

I would like to use this for memory mapping of huge compressed raster file. Used compression algorithm allows fast block decompression. User-defined loading function would decompress the file page by page on the fly.

The compressed files are read-only. User-space solution is preferred.

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Is it possible to overload memory mapped file loader? In case of page fault, Linux kernel would not load the requested data from disk, but instead of it, user-defined function would be called, which would fill the memory page.

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It is possible and some libraries do just that. See <a href="https://www.gnu.org/software/libsigsegv/" rel="nofollow">libsigsegv</a>.

Install a signal handler for SIGSEGV with sigaction using the following signature for your handler:

void sigsegv_handler(int, siginfo_t* si, void*) { si->si_addr; // Memory location which caused the page fault. // mmap the missing page and return here // On error alternatives: // * restore the previous SIGSEGV handler and return (the default one dumps core), or // * abort() (dumps core), or // * _exit(EXIT_FAILURE). }