Advice for strange kernel error

[brett]

I noticed in my kernel log the following:

** WARNING: Currently emulating unsupported memory accesses **
** in /lib/tls libraries. The emulation is very **
** slow, and may not work correctly with all **
** programs (e.g., some may 'Segmentation fault'). **
** TO ENSURE FULL PERFORMANCE AND CORRECT FUNCTION, **
** YOU MUST EXECUTE THE FOLLOWING AS ROOT: **
** mv /lib/tls /lib/tls.disabled **

A quick google search reveals that this concerns Xen, but doesn't really offer any suggestions.

I'd rather not go around renaming stuff in /lib without knowing exactly why I am, so can anyone offer any advice?

The rest of the kernel and system logs offer nothing relevant...

[matta]

Yes... run "mv /lib/tls /lib/tls.disabled" or else your performance will suffer.

[brett]

[QUOTE=matta]Yes... run "mv /lib/tls /lib/tls.disabled" or else your performance will suffer.[/QUOTE]

But any hints as to the reason for this message?

[speedbird]

[QUOTE=matta]Yes... run "mv /lib/tls /lib/tls.disabled" or else your performance will suffer.[/QUOTE]

I happen to have both directories in my VPS :eek:

diff'ing them results in both folders being considerabily different (in contents and diffs in files with the same name)

uhm, is this normal?

TIA,

-- sb

[matta]

It doesn't matter whats in them. TLS is the new glibc/kernel threading code and Xen doesn't support it natively, it's through emulation that it will let it "work". If the /lib/tls directory exists then glibc will use TLS support, if not it will fall back to the standard non-tls libraries and you'll remove the emulation layer for much better performance.

There is a patch to glibc to fully support TLS under Xen, but it hasn't had much testing and i'd recommend against using it... although you can search and experiment if you wish.

[speedbird]

[QUOTE=matta]It doesn't matter whats in them. TLS is the new glibc/kernel threading code and Xen doesn't support it natively, it's through emulation that it will let it "work". If the /lib/tls directory exists then glibc will use TLS support, if not it will fall back to the standard non-tls libraries and you'll remove the emulation layer for much better performance.[/QUOTE]

So, will it be safe to do a mv tld tld.disabled.1 in case I already have both dirs? - I assume a reboot of the VPN will be in order, right?

I have not had any prolems with my system, in fact it is running pretty smooth, maybe a little bit too smooth :) from what I am used to in a system like this (Python & Zope). Thanks for the responses.

-- sb

[matta]

Oh... I see the confusion. Yes, you can move /lib/tls to anything else, even delete it if you like. The main purpose is to enure that /lib/tls itself does not exist, tls.disabled is just "recommended" renaming.

I'd recommend rebooting after you do the move as the TLS libraries will already be in memory.