When I build a kext that uses IOLockSleepDeadline and IOLockWakeup with Xcode 7 with the MacOSX10.11.sdk, the resulting kext will not load on OS X 10.8 (even though I am specifying MACOSX_DEPLOYMENT_TARGET=10.8 and -mmacosx-version-min=10.8).
Trying to load the resulting kext on 10.8 yeilds:
(kernel) kxld[com.mykext]: The following symbols are unresolved for this kext:
(kernel) kxld[com.mykext]: _IOLockSleepDeadline_darwin14
(kernel) kxld[com.mykext]: _IOLockWakeup_darwin14
(kernel) Can't load kext com.mykext - link failed.It looks like by the very act of compiling against the 10.11 headers (particularly IOLocks.h), the "_darwin14" part is being appended.
However, building using Xcode 5.1.1 with MacOSX10.9.sdk, the resulting kext loads on both 10.8 and 10.11 without modifications.
In the 10.11 IOLocks.h, there are three definitions:
int IOLockSleep( IOLock * lock, void *event, UInt32 interType) __DARWIN14_ALIAS(IOLockSleep);
int IOLockSleepDeadline( IOLock * lock, void *event, AbsoluteTime deadline, UInt32 interType) __DARWIN14_ALIAS(IOLockSleepDeadline);
void IOLockWakeup(IOLock * lock, void *event, bool oneThread) __DARWIN14_ALIAS(IOLockWakeup);And in the 10.8 IOLocks.h, the same definitions are:
int IOLockSleep( IOLock * lock, void *event, UInt32 interType);
int IOLockSleepDeadline( IOLock * lock, void *event, AbsoluteTime deadline, UInt32 interType);
void IOLockWakeup(IOLock * lock, void *event, bool oneThread);That is, the "__DARWIN14_ALIAS" macro is mangling the function names in the 10.11 headers. Where I'm explicitly compiling for 10.8 (darwin 12, if I'm understanding the numbering correctly), it doesn't surprise me that the _darwin14 variants of the functions don't exist in the 10.8 kernel.
What is the best way to approach this?
