On Fri, Jul 30, 2010 at 02:28:47AM +0000, YAMAMOTO Takashi wrote: > > Hi all, > > I'm working on Thread Locale Storage support for NetBSD and I am facing > > an interesting issue with the libpthread integration. On i386 and AMD64, > > TLS support uses the segment register %gs or %fs to load the thread > > pointer. The location used as segment base is thread specific and stored > > in the PCB. It is not part of ucontext_t and therefore _lwp_makecontext > > can't store private in it. To work around this, I can think of three > > options: > > > > (1) Break ucontext_t and allow the private pointer as separate field > > > > Pro: Integrates nicely with the other platforms and debugger > > Contra: Lots of nasty interfaces to deal with in terms of compat. > > > > (2) Add private as argument for _lwp_create as well. > > > > Pro: logically fits well too, minimal amount of changes for libc and > > libpthread. > > > > (3) Defer calling _lwp_setprivate into the newly created thread. > > > > Pro: no kernel / libc changes needed > > Contra: might create complications with signal handlers etc > > > > > > I'm personally favoring (2), but looking for input. > > > > Joerg > > when i looked at this, i abused _REG_ESP for i386. > http://mail-index.netbsd.org/tech-kern/2009/09/27/msg006146.html > i have no idea if other ports have unused members like this, tho.
I don't think that is going to work for this. The stack pointer is needed for the stack location of the newly created thread, isn't it? Joerg