Who understands this code?

Greg Schafer gschafer at zip.com.au
Fri Mar 14 03:39:35 PST 2003


On Fri, Mar 14, 2003 at 10:04:40PM +1100, Greg Schafer wrote:
> No, of course not :-) I live in tweak city, remember? The only 2 tweaks I
> can think of that could possibly be pertinent here are 1) the whole shebang
> was compiled with -march=i686 and 2) glibc was configured with
> --enable-kernel=current (i.e. 2.4.20)

--enable-kernel definitely enables different code paths relevant to mmap.

This from "unix/sysv/linux/kernel-features.h"

/* On x86 the mmap2 syscall was introduced in 2.3.31.  */
#if __LINUX_KERNEL_VERSION >= 131871 && defined __i386__
# define __ASSUME_MMAP2_SYSCALL 1
#endif

And this from "unix/sysv/linux/i386/mmap.S"

/* I don't think it is worthwhile trzing to use mmap2 whenever it
   is available.  Only use it when we are sure the syscall exists.  */
#ifdef __ASSUME_MMAP2_SYSCALL

<do asm stuff snipped>

#else

<do other asm stuff snipped>

Dunno, this is getting out of my league. I'spose I'll just have to recompile
not using --enable-kernel and see what happens.

Greg
-- 
Unsubscribe: send email to listar at linuxfromscratch.org
and put 'unsubscribe lfs-dev' in the subject header of the message



More information about the lfs-dev mailing list