> NPTL TLS, as implemented by GLIBC by default, works under xen but
> has severe performance problems due to the implementation
> technique. So... recompile glibc with -mno-tls-direct-seg-refs , as
> indicated in http://wiki.xensource.com/xenwiki/XenSpecificGlibc
> *** All well and good, but just in case: might sbcl
> itself be generating native code that use segment offsets
> in a Xen-unfriendly manner?
Not if I understand their description of the problem correctly.
Threaded x86 SBCL uses segments a lot (for example on every dynamic
variable access), but only with positive offsets.