[aarch64-port-dev ] RFR(XXS) JDK-8154379: MIN_STACK_SHADOW_PAGES should equal DEFAULT_STACK_SHADOW_PAGES on aarch64

[Chris Plummer]

On 4/20/16 4:53 AM, Edward Nevill wrote:
> Hi Chris,
>
> On Tue, 2016-04-19 at 09:25 -0700, Chris Plummer wrote:
>> Hello,
>>
>> Please review the following diff. I would appreciate it if someone could
>> verify that the open aarch64 port still runs properly after this change.
>> Testing with just "bin/java" should be enough.
>>
>> https://bugs.openjdk.java.net/browse/JDK-8154379
>>
>> diff --git a/src/cpu/aarch64/vm/globals_aarch64.hpp
>> b/src/cpu/aarch64/vm/globals_aarch64.hpp
>> --- a/src/cpu/aarch64/vm/globals_aarch64.hpp
>> +++ b/src/cpu/aarch64/vm/globals_aarch64.hpp
>> @@ -50,7 +50,7 @@
>>
>>    #define MIN_STACK_YELLOW_PAGES 1
>>    #define MIN_STACK_RED_PAGES    1
>> -#define MIN_STACK_SHADOW_PAGES 1
>> +#define MIN_STACK_SHADOW_PAGES DEFAULT_STACK_SHADOW_PAGES
>>    #define MIN_STACK_RESERVED_PAGES (0)
>>
>>    define_pd_global(intx, StackYellowPages, DEFAULT_STACK_YELLOW_PAGES);
> I have patched this and tested it extensively (*).
>
> However I wonder if the correct fix is not to back out the following changeset completely? I have also tested this extensively (*).
>
> --- cut here ---
> # HG changeset patch
> # User enevill
> # Date 1445940528 0
> #      Tue Oct 27 10:08:48 2015 +0000
> # Node ID 0ecd612047de30414112300f6d315e4fce5c55ee
> # Parent  e7b4c40ebb110615f2ad3be549fd3f2adf0c44a4
> 8140582: aarch64: jvm fails to initialise after 8078556
> Summary: jvm fails to initialise on aarch64 systems with pagesize > 4K
> Reviewed-by: duke
>
> diff -r e7b4c40ebb11 -r 0ecd612047de src/cpu/aarch64/vm/globals_aarch64.hpp
> --- a/src/cpu/aarch64/vm/globals_aarch64.hpp    Tue Oct 27 01:45:01 2015 -0400
> +++ b/src/cpu/aarch64/vm/globals_aarch64.hpp    Tue Oct 27 10:08:48 2015 +0000
> @@ -59,9 +59,9 @@
>   #define DEFAULT_STACK_RED_PAGES (1)
>   #define DEFAULT_STACK_SHADOW_PAGES (4 DEBUG_ONLY(+5))
>   
> -#define MIN_STACK_YELLOW_PAGES DEFAULT_STACK_YELLOW_PAGES
> -#define MIN_STACK_RED_PAGES DEFAULT_STACK_RED_PAGES
> -#define MIN_STACK_SHADOW_PAGES DEFAULT_STACK_SHADOW_PAGES
> +#define MIN_STACK_YELLOW_PAGES 1
> +#define MIN_STACK_RED_PAGES    1
> +#define MIN_STACK_SHADOW_PAGES 1
>   
>   define_pd_global(intx, StackYellowPages, DEFAULT_STACK_YELLOW_PAGES);
>   define_pd_global(intx, StackRedPages, DEFAULT_STACK_RED_PAGES);
> --- cut here ---
>
> Backing this out reverts the MIN YELLOW/RED/SHADOW to DEFAULT YELLOW/RED/SHADOW which seems the correct thing to do.
>
> The above changeset ( https://bugs.openjdk.java.net/browse/JDK-8140582 ) was to workaround problems introduced by ( https://bugs.openjdk.java.net/browse/JDK-8078556 )
>
> However this has been resolved by ( https://bugs.openjdk.java.net/browse/JDK-8139864 ) so the above change should not be necessary and can be back out.
>
> All the best,
> Ed.
>
> (*) I ran java DhryStone
>
>
Hi Ed,

I think the full backout as you suggest makes sense. I can do that. 
Thanks for testing.

Chris