RFR 8017061: os_bsd.cpp contains code for UseSHM and UseHugeTLBFS

[Gerard Ziemski]

> On Oct 18, 2018, at 8:24 PM, David Holmes <david.holmes at oracle.com> wrote:
> 
> On 18/10/2018 11:35 PM, Gerard Ziemski wrote:
>>> On Oct 17, 2018, at 8:38 PM, David Holmes <david.holmes at oracle.com> wrote:
>>> 
>>> Hi Gerard,
>>> 
>>> On 18/10/2018 3:14 AM, Gerard Ziemski wrote:
>>>> Thank you for your reviews.
>>>>> On Oct 16, 2018, at 6:52 PM, David Holmes <david.holmes at oracle.com> wrote:
>>>>> 
>>>>> Hi Gerard,
>>>>> 
>>>>> On 17/10/2018 2:04 AM, Gerard Ziemski wrote:
>>>>>> hi David,
>>>>>> Thank you for the review.
>>>>>>> On Oct 16, 2018, at 1:48 AM, David Holmes <david.holmes at oracle.com> wrote:
>>>>>>> 
>>>>>>> Hi Gerard,
>>>>>>> 
>>>>>>> On 16/10/2018 5:41 AM, Gerard Ziemski wrote:
>>>>>>>> Hi all,
>>>>>>>> Please review this small fox that removes code from bsd platform, which implements unused (and untested) UseLargePages support.
>>>>>>> 
>>>>>>> Removal seems okay but I think you can also remove:
>>>>>>> 
>>>>>>> ./os/bsd/globals_bsd.hpp:  product(bool, UseSHM, false,
>>>>>>> ./os/bsd/globals_bsd.hpp:  product(bool, UseHugeTLBFS, false,
>>>>>> If I remove “UseSHM” and “UseHugeTLBFS” they will stop being accepted on BSD platform, though the documentation says it’s Linux only. Would I need to obsolete them? If so, how to obsolete a flag on just one platform?
>>>>> 
>>>>> I think if you #ifdef the entry in the obsolete flags table that would do it. This is a rare occurrence. Obsolete in 12 and expire in 13.
>>>> Fixed.
>>>> Webrev: http://cr.openjdk.java.net/~gziemski/8017061_rev2
>>> 
>>> The flags are obsoleted not deprecated, they should be removed from the globals_bsd.hpp file.
>> If I remove them, then VM will no longer accept them and refuse to run. I though that the purpose of the deprecate/obsolete/expire exercise is to allow the VM to accept the flags in question, so developers have the time to adapt, and only remove them later?
> 
> You don't understand the deprecation/obsoletion/expiration process.
> 
> Deprecation:
> - the code using the flag exists and works as normal
> - the flag continues to exist in globals.hpp (or variants)
> - the flag is listed as deprecated in the arguments.cpp table, for the current version, and may have future obsoletion and expiration versions
> - if the flag is used then a deprecation warning is issued
> 
> Obsoletion:
> - the code using the flag is completely removed (assuming the flags default value if appropriate)
> - the flag is removed from globals.hpp (or variants)
> - the table in arguments.cpp lists the flag as obsoleted in the current release
> - if the flag is used then an obsoletion warning is issued
> 
> Expiration
> - the flag is removed from the table in arguments.cpp
> - if the flag is used the VM terminates with an "unknown VM option" error

Thank you for the explanations.

Webrev: http://cr.openjdk.java.net/~gziemski/8017061_rev3
Testing: Mach5 hs_tier1-6 (in progress…)


cheers