/*
* Initialize the context management stuff.
@@ -326,13 +344,56 @@ void __init mmu_context_init(void)
init_mm.context.active = NR_CPUS;
/*
+ * The MPC8xx has only 16 contexts. We rotate through them on
each
+ * task switch. A better way would be to keep track of tasks that
+ * own contexts, and implement an LRU usage. That way very active
+ * tasks don't always have to pay the TLB reload overhead. The
+ * kernel pages are mapped shared, so the kernel can run on behalf
+ * of any task that makes a kernel entry. Shared does not mean they
+ * are not protected, just that the ASID comparison is not
performed.
+ * -- Dan
+ *
+ * The IBM4xx has 256 contexts, so we can just rotate through these
+ * as a way of "switching" contexts. If the TID of the TLB is zero,
+ * the PID/TID comparison is disabled, so we can use a TID of zero
+ * to represent all kernel pages as shared among all contexts.
can expand the comment of change it to say all other nonhash parts
40x, 4xx, fsl-booke right now have 256 contexts.
+ * -- Dan
+ */
+ if (mmu_has_feature(MMU_FTR_TYPE_8xx)) {
+ first_context = 0;
+ last_context = 15;
+ } else {
+ first_context = 1;
+ last_context = 255;
+ }
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