Implement a facility for dynamic per-cpu variables.

 - Modules and kernel code alike may use DPCPU_DEFINE(),
   DPCPU_GET(), DPCPU_SET(), etc. akin to the statically defined
   PCPU_*.  Requires only one extra instruction more than PCPU_* and is
   virtually the same as __thread for builtin and much faster for shared
   objects.  DPCPU variables can be initialized when defined.
 - Modules are supported by relocating the module's per-cpu linker set
   over space reserved in the kernel.  Modules may fail to load if there
   is insufficient space available.
 - Track space available for modules with a one-off extent allocator.
   Free may block for memory to allocate space for an extent.

Reviewed by:    jhb, rwatson, kan, sam, grehan, marius, marcel, stas

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/sparc64/include/pcpu.h b/sys/sparc64/include/pcpu.h
index efb5174..7d2f5a0 100644
--- a/sys/sparc64/include/pcpu.h
+++ b/sys/sparc64/include/pcpu.h
@@ -62,6 +62,8 @@ struct pmap;
 
 #ifdef _KERNEL
 
+extern void *dpcpu0;
+
 struct pcb;
 struct pcpu;