diff options
Diffstat (limited to 'proc.h')
| -rw-r--r-- | proc.h | 17 |
1 files changed, 9 insertions, 8 deletions
@@ -59,10 +59,9 @@ struct cpu { int ncli; // Depth of pushcli nesting. int intena; // Were interrupts enabled before pushcli? - // "Thread"-local storage variables + // Cpu-local storage variables; see below struct cpu *cpu; struct proc *proc; - void *tlsstruct; }; extern struct cpu cpus[NCPU]; @@ -70,9 +69,11 @@ extern int ncpu; // Per-CPU variables, holding pointers to the // current cpu and to the current process. -// The __thread prefix tells gcc to refer to them in the segment -// pointed at by gs; the name __thread derives from the use -// of the same mechanism to provide per-thread storage in -// multithreaded user programs. -extern __thread struct cpu *cpu; // This cpu. -extern __thread struct proc *proc; // Current process on this cpu. +// The asm suffix tells gcc to use "%gs:0" to refer to cpu +// and "%gs:4" to refer to proc. ksegment sets up the +// %gs segment register so that %gs refers to the memory +// holding those two variables in the local cpu's struct cpu. +// This is similar to how thread-local variables are implemented +// in thread libraries such as Linux pthreads. +extern struct cpu *cpu asm("%gs:0"); // This cpu. +extern struct proc *proc asm("%gs:4"); // Current proc on this cpu. |