Messages in this thread | | | Date | Sun, 21 Mar 2004 10:51:16 +0100 | From | Ingo Molnar <> | Subject | Re: sched_setaffinity usability |
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* Helge Hafting <helgehaf@aitel.hist.no> wrote:
> Let the compile create that info file. Then handle it much like a > module, except that it is a "module" without any code. I.e. copy it > to /lib/modules/<kernelversion> if installing modules, or stuff the > file into the initrd if making an initrd. > > Now it is in a place specific to the kernel, where a library can find > it.
this has a couple of disadvantages:
- the kernel can pre-map the 'file' cheaper - in fact on x86 it's zero-cost currently. Mapping a file takes 3 syscalls and at least one pagefault. Since glibc needs a good portion of this info for absolutely every ELF binary, why not provide it in a preconstructed way? x86 is doing it via the VDSO. ia64 and x86-64 is doing it via a dso-alike mechanism.
- obtaining the kernel version currently needs one more syscall [uname()].
- the 'metadata' becomes detached from the kernel image, so it cannot contain 'crutial' data. Testing kernels becomes harder, etc. (until now i could just send a bzImage to someone to get it tested - now it would have to include the metadata too.)
- it excludes non-build-time data.
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