Nicolas, Thanks for the explanation. :) I noticed what you mentioned. Actually, Kconfig says TLS EMU might be used in some "old" (e.g. pre-armv6) SMP platforms without TLS register. In such a case, could we still ensure it's SMP safe by a single ldr? Thanks, Lea On Fri, Apr 8, 2011 at 9:19 PM, Nicolas Pitre <nico@xxxxxxxxxxx> wrote: > On Fri, 8 Apr 2011, Li Li wrote: > >> Dears, >> >> I cannot understand how TLS EMU ensure it's SMP safe, because get_tls >> helper (at 0xffff0fe0) just read the value from 0xffff0ff0. But all >> SMP cores should have the exact same mapping to the vectors page (at >> 0xffff0000). So various threads running on different SMP cores at the >> same time would get the same emulated TLS value (instead of thread >> specific value set via set_tls). Could anybody explain this a little >> bit? > > On SMP the hardware TLS register is always available, therefore the TLS > value is not stored at 0xffff0ff0. The code actually installed at > 0xffff0fe0 is modified at boot time by kuser_get_tls_init to select > either the ldr or the mrc instruction to retrieve the TLS value. > > > Nicolas > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
