* Re: [Qemu-devel] [PATCH] exec.c: Clarify comment about tlb_flush() flush_global parameter
2012-01-17 13:23 [Qemu-devel] [PATCH] exec.c: Clarify comment about tlb_flush() flush_global parameter Peter Maydell
@ 2012-01-30 12:04 ` Peter Maydell
2012-01-30 13:10 ` Andreas Färber
2012-02-01 22:11 ` Anthony Liguori
2 siblings, 0 replies; 4+ messages in thread
From: Peter Maydell @ 2012-01-30 12:04 UTC (permalink / raw)
To: qemu-devel
Cc: Blue Swirl, Aurelien Jarno, Alexander Graf,
陳韋任, patches
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
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH] exec.c: Clarify comment about tlb_flush() flush_global parameter
2012-01-17 13:23 [Qemu-devel] [PATCH] exec.c: Clarify comment about tlb_flush() flush_global parameter Peter Maydell
2012-01-30 12:04 ` Peter Maydell
@ 2012-01-30 13:10 ` Andreas Färber
2012-02-01 22:11 ` Anthony Liguori
2 siblings, 0 replies; 4+ messages in thread
From: Andreas Färber @ 2012-01-30 13:10 UTC (permalink / raw)
To: Peter Maydell
Cc: qemu-trivial, patches, qemu-devel, 陳韋任,
Alexander Graf
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;
--
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH] exec.c: Clarify comment about tlb_flush() flush_global parameter
2012-01-17 13:23 [Qemu-devel] [PATCH] exec.c: Clarify comment about tlb_flush() flush_global parameter Peter Maydell
2012-01-30 12:04 ` Peter Maydell
2012-01-30 13:10 ` Andreas Färber
@ 2012-02-01 22:11 ` Anthony Liguori
2 siblings, 0 replies; 4+ messages in thread
From: Anthony Liguori @ 2012-02-01 22:11 UTC (permalink / raw)
To: Peter Maydell
Cc: patches, qemu-devel, 陳韋任, Alexander Graf
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;
^ permalink raw reply [flat|nested] 4+ messages in thread