From 771124e1a61f73886ab16b4c9ce01eeffb74ce2b Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Tue, 17 Jan 2012 13:23:13 +0000 Subject: exec.c: Clarify comment about tlb_flush() flush_global parameter Clarify the comment about tlb_flush()'s flush_global parameter, so it is clearer what it does and why it is OK that the implementation currently ignores it. Reviewed-by: Andreas F=C3=A4rber Signed-off-by: Peter Maydell Signed-off-by: Anthony Liguori --- exec.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'exec.c') diff --git a/exec.c b/exec.c index 5b9eb9aa1..b81677ade 100644 --- a/exec.c +++ b/exec.c @@ -1876,8 +1876,18 @@ static CPUTLBEntry s_cputlb_empty_entry = { .addend = -1, }; -/* NOTE: if flush_global is true, also flush global entries (not - implemented yet) */ +/* NOTE: + * If flush_global is true (the usual case), flush all tlb entries. + * If flush_global is false, flush (at least) all tlb entries not + * marked global. + * + * Since QEMU doesn't currently implement a global/not-global flag + * for tlb entries, at the moment tlb_flush() will also flush all + * tlb entries in the flush_global == false case. This is OK because + * CPU architectures generally permit an implementation to drop + * entries from the TLB at any time, so flushing more entries than + * required is only an efficiency issue, not a correctness issue. + */ void tlb_flush(CPUState *env, int flush_global) { int i; -- cgit v1.2.3