Posted Jul 24, 2005 21:39 UTC (Sun) by jreiser
In reply to: NPTL Support?
Parent article: OLS: Xen and UML
Yes, NPTL is Native Posix Thread Library. Supporting "full Linux [user-mode] processes" implies supporting the kernel pieces that support NPTL. The major pieces are the syscalls clone, set_thread_area, and set_tid_address; the support for segment %gs [on x86 and amd64]; etc. Both UML and Xen must do this in order to run an arbitrary user process. NPTL might be used as the thread model for a multithreaded single process web server, mail server, etc., which runs under UML or Xen in order to increase isolation, security, management flexibility, etc. On x86, glibc has a special compiletime option to support Xen by avoiding "negative" offsets to %gs, which have significantly higher implementation costs than "positive" offsets.
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