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    Subject[RFC] ARM binutils feature churn causing kernel problems

    The ARM binutils seems to be in a problematical state at the moment.
    It has recently had a "bug" fixed where ARM specific "mapping symbols"
    were not generated in ELF objects. These "mapping symbols" have names
    such as "$a" and "$d".

    The unfortunate problem is that "$a" nearly always corresponds with
    the same address as the name of a function - and since none of the
    kernel knows about these "mapping symbols" we see backtraces which
    effectively say:

    [<address>] ($a+0xfoo/0xbar) from [<address>] ($a+0xfoo/0xbar)

    in other words, the kallsyms table and the symbol tables from kernel
    modules are next to useless because it invariably decodes all addresses
    to functions named "$a".

    While the binutils people have (we believe) fixed "ld" to ignore
    these symbols when decoding to a function name, "nm" reveals these

    It may be true that this will cause a lot of stuff which parses
    ELF objects to break, and I'm not going to debate whether the whole
    idea is a good one or bad. However, what are peoples (Rusty's in
    particular) to adding yet more ARM binutils specific hacks to the
    kernel to work around these continuing problems?

    My major worry is that ARM ELF format will end up having soo many
    extra "features" that the Linux kernel, if it's going to continue
    supporting ARM, will need a fair amount of code to make all these
    features "work" as expected.

    Russell King
    Linux kernel 2.6 ARM Linux -
    maintainer of: 2.6 PCMCIA -
    2.6 Serial core
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