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

[John Coomes]

Erik Joelsson (erik.joelsson at oracle.com) 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/

The hotspot changes look good to me.

-John

> 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