| Message ID | 1326806593-21785-1-git-send-email-peter.maydell@linaro.org |
|---|---|
| State | Accepted |
| Commit | 771124e1a61f73886ab16b4c9ce01eeffb74ce2b |
| Headers | show |
Ping? -- PMM On 17 January 2012 13:23, Peter Maydell <peter.maydell@linaro.org> wrote: > 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. > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > --- > Minor clarification following a conversation on IRC... > > exec.c | 14 ++++++++++++-- > 1 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/exec.c b/exec.c > index 7f9f730..f667cf0 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; > -- > 1.7.1 > >
Am 17.01.2012 14:23, schrieb Peter Maydell: > 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. > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Andreas Färber <afaerber@suse.de> CC'ing qemu-trivial. Andreas > --- > Minor clarification following a conversation on IRC... > > exec.c | 14 ++++++++++++-- > 1 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/exec.c b/exec.c > index 7f9f730..f667cf0 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;
On 01/17/2012 07:23 AM, Peter Maydell wrote: > 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. > > Signed-off-by: Peter Maydell<peter.maydell@linaro.org> Applied. Thanks. Regards, Anthony Liguori > --- > Minor clarification following a conversation on IRC... > > exec.c | 14 ++++++++++++-- > 1 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/exec.c b/exec.c > index 7f9f730..f667cf0 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;
diff --git a/exec.c b/exec.c index 7f9f730..f667cf0 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;
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. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- Minor clarification following a conversation on IRC... exec.c | 14 ++++++++++++-- 1 files changed, 12 insertions(+), 2 deletions(-)