[PATCH v2] Documentation / cpu hotplug: Rephrase the outdated description for MADT entries

[PATCH v2] Documentation / cpu hotplug: Rephrase the outdated description for MADT entries

[Hanjun Guo]

More than 256 entries in ACPI MADT is supported from ACPI 3.0, so the
information should be updated.

-v2: Rephrase the information instead of simply removing it according
to Rafael's advice.

Suggested-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
---
 Documentation/cpu-hotplug.txt |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index 9f40135..67f733d 100644
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -370,8 +370,10 @@ A: There is no clear spec defined way from ACPI that can give us that
    CPUs in MADT as hotpluggable CPUS.  In the case there are no disabled CPUS
    we assume 1/2 the number of CPUs currently present can be hotplugged.
 
-   Caveat: Today's ACPI MADT can only provide 256 entries since the apicid field
-   in MADT is only 8 bits.
+   Caveat: ACPI MADT can only provide 256 entries in systems with only ACPI 2.0c
+   or earlier ACPI version supported, because the apicid field in MADT is only
+   8 bits. From ACPI 3.0, this limitation was removed since the apicid field
+   was extended to 32 bits with x2APIC introduced.
 
 User Space Notification
 
-- 
1.7.9.5

Re: [PATCH v2] Documentation / cpu hotplug: Rephrase the outdated description for MADT entries

[Rafael J. Wysocki]

On Friday, June 21, 2013 05:09:18 PM Hanjun Guo wrote:
> More than 256 entries in ACPI MADT is supported from ACPI 3.0, so the
> information should be updated.
> 
> -v2: Rephrase the information instead of simply removing it according
> to Rafael's advice.

Queued up for 3.11.

Thanks,
Rafael


> Suggested-by: Rafael J. Wysocki <rjw@sisk.pl>
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> ---
>  Documentation/cpu-hotplug.txt |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
> index 9f40135..67f733d 100644
> --- a/Documentation/cpu-hotplug.txt
> +++ b/Documentation/cpu-hotplug.txt
> @@ -370,8 +370,10 @@ A: There is no clear spec defined way from ACPI that can give us that
>     CPUs in MADT as hotpluggable CPUS.  In the case there are no disabled CPUS
>     we assume 1/2 the number of CPUs currently present can be hotplugged.
>  
> -   Caveat: Today's ACPI MADT can only provide 256 entries since the apicid field
> -   in MADT is only 8 bits.
> +   Caveat: ACPI MADT can only provide 256 entries in systems with only ACPI 2.0c
> +   or earlier ACPI version supported, because the apicid field in MADT is only
> +   8 bits. From ACPI 3.0, this limitation was removed since the apicid field
> +   was extended to 32 bits with x2APIC introduced.
>  
>  User Space Notification
>  
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.