Re: cannot set up LDT for thread-local storage

[Thor Lancelot Simon <tls%rek.tjls.com@localhost>]

On Thu, Oct 02, 2008 at 07:43:24PM -0500, John Hayward wrote:
>> I found pr 33487.
>> This was for dom0 i386 for NetBSD 3.99.19.
>>
>> I have been running a version of firefox-linux on a dom0 i386 
>> NetBSD-4.0 without problem.  Maybe I was just lucky.
> Here is additional info
> Xen 3.0 i386  dom0 NetBSD-4.0  i386 dom0 firefox-linux-2 works
> Xen 3.3 amd64 dom0 NetBSD-4.99 i386 domu firefox-linux-2 works
> Xen 3.3 amd64 dom0 NetBSD-4.99 i386 domu firefox-linux-3 causes panic
>        (with LDT option on)

This is an artifact of which Linux pthread library the application's
linked to.  The old library used a method of allocation for thread local
storage which Xen couldn't efficiently accomodate, so under Xen it was
slow as molasses.  The new one uses a method which requires adjusting
the processor's LDT (note that, oddly enough, NetBSD's libpthread
requires neither).  Unfortunately, the USER_LDT option doesn't work
right under NetBSD/xen.

One suspects there might be a hungry grad student out there whou coudl
be slipped a few hundred bucks to fix this -- but (I not being at
present a hungry grad student) that's just a hunch.

You could run a native NetBSD firefox3 binary -- they seem to work OK,
FWIW.

Thor