More glibc's

Kevin P. Fleming kpfleming at
Wed Nov 26 06:40:54 PST 2003

Greg Schafer wrote:

> Kevin, that technique only works on a RH system. Setting that variable on an
> LFS system doesn't do much at all.

Ahh, that explains why I've only seen it in knowledge base articles 
about running binary apps on RedHat Linux :-)

> Essentially, what they do is install separate libc's in different paths
> e.g. /lib/tls, /lib/i686 and so forth. By setting that variable, they can
> control which libc gets loaded at runtime. Debian have just started doing it
> too.

Tricky, that must be fun to manage on their end, keeping track of 
patches and security problems for multiple libc versions.

> I've studied the Glibc sources to try and figure out how it works. It's
> really quite clever and fascinating and worth looking into if you're
> interested. Grep for "hwcap". It's also worth studying the RH spec file. The
> "--enable-kernel=" switch plays a role. Overall, the technique is very
> useful for distros, not much use for LFS.

Thanks for the info.

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