Review Request: 8008451: Make mac builds on 10.8 work on 10.7

[Daniel D. Daugherty]

Widening the NotSpot net from just Runtime to all of HotSpot...

Dan


On 2/20/13 7:52 AM, Erik Joelsson wrote:
> I was wrong, just setting the macros below did not generate 10.7 
> compatible bits when built on 10.8. Since I already pushed the old 
> solution (except for hotspot), I created a new bug. Here is a new set 
> of patches, combining -DMAC_OS_X_VERSION_MAX_ALLOWED=1070 and 
> -mmacosx-version-min=10.7.0 and also setting the latter on the link 
> command line. This combination both generates compatible binaries and 
> treats newer API calls as errors, all verified.
>
> Sine the two parameters take their argument in different formats, the 
> handling of defaults is a bit more complicated. The variable being 
> sent around and that you can override on the command line is now 
> MACOSX_VERSION_MIN=10.7.0, matching the parameter to the compiler/linker.
>
> It would be good if someone from hotspot could review the hotspot 
> changes.
>
> http://cr.openjdk.java.net/~erikj/8008451/webrev.hotspot.01/
> http://cr.openjdk.java.net/~erikj/8008451/webrev.root.01/
> http://cr.openjdk.java.net/~erikj/8008451/webrev.jdk.01/
>
> /Erik
>
> On 2013-02-15 10:49, Erik Joelsson wrote:
>>
>>
>> On 2013-02-15 09:43, Erik Joelsson wrote:
>>>
>>> On 2013-02-14 18:04, David DeHaven wrote:
>>>>> Here are a series of patches that adds the following to all native 
>>>>> compile lines on macosx:
>>>>>
>>>>> -DMAC_OS_X_VERSION_MAX_ALLOWED=1070 
>>>>> -DMAC_OS_X_VERSION_MIN_REQUIRED=1070
>>>> I know I'm not a reviewer, but I have an opinion anyways :)
>>>>
>>>> Using "-mmacosx-version-min=10.7" seems more appropriate for the 
>>>> latter, this is passed to the linker as well which I believe sets 
>>>> version information in the Mach-O headers (in the form of a load 
>>>> command) to prevent it from being loaded on older systems. The 
>>>> MIN_REQUIRED macro is set to a value that matches what's passed to 
>>>> the -mmacosx-version-min argument, so it doesn't need to be provided.
>>>>
>>>>
>>> The effect of the -mmacosx-version-min=10.7 when sent to the linker 
>>> is to make any calls to newer APIs "softlinked". This means the 
>>> library will still load fine on the older OS, but the application is 
>>> responsible for only actually making the newer calls if they are 
>>> available. This is a good feature if you knowingly want to support 
>>> multiple versions of the OS and still use features in the newer OS 
>>> when available. I do not believe we have the need for that and if we 
>>> ever do, then these parameters will need to change.
>>>
>> It's true -mmacosx-version-min= also sets the macro 
>> MAC_OS_X_VERSION_MIN_REQUIRED=, but I see no gain in changing just 
>> one of them to something else just because it works. The format of 
>> the parameter is also different (10.7 vs 1070) which would require us 
>> to add logic for converting between the two.
>>
>> /Erik