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    SubjectRe: older kernels + new glibc?
        Hi Richard :)

    * Richard B. Johnson <> dixit:
    [Kernel-related userspace tools]
    > That's why you should use an 'include' search path on the
    > compiler command line when you are compiling these. The search
    > path should point to the kernel headers of the version you
    > intend to use. The kernel tries to remain compatible, but
    > when you access internal structures, compatibility may be lost.

    So, as a rule of thumb, anytime I compile or install such
    programs, I should set an include search path for them.

    > > If I've understood correctly, these tools (like hdparm) should
    > > *not* use current (running) kernel headers, but those that were in
    > > use when glibc was built, am I right? Which, BTW, is a big problem
    > > because I don't have the slightest idea about which kernel was in use
    > > when I built my glibc.
    > Yes. One can usually 'trust' a distribution and use whatever they
    > shipped.

    I don't use a distro, I have a do-it-yourself linux box, part of
    it is from an old Debian 1.3.1, but most of it is hand-made. I
    compile my own kernel-related tools. I suppose that, for each package
    I install that may be kernel-related, I should do 'grep "<linux/"'
    just in case...

    > > But putting under /usr/include/linux and /usr/include/asm the
    > > headers in use when glibc is built can lead to a problem, too.
    > > Imagine that at some point in the future, the contents of the asm or
    > > linux dirs depends on which facilities the kernel has configured
    > > e.g. no scsi.h if no scsi support is present in the configured
    > > kernel. That way, you don't have scsi.h under your
    > > /usr/include/linux, but you may need it if you add an SCSI card with
    > > your running kernel and want to compile some 'scsiutils' or whatever
    > > like that.
    > No. User-mode programs must never, never, never, ever include
    > kernel headers directly. Instead, if they are for kernel utilities,
    > the include search-path must be explicitly set.

    Nice. But I don't feel it is current practice... For example,
    hdparm doesn't set such include search path, iproute2 does but
    modutils (up to 2.4.27, AFAIK) doesn't... I don't know many more
    examples, so I may well be wrong.

    Raúl Núñez de Arenas Coronado

    Linux Registered User 88736 &
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