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History log of /src/lib/libc/arch/powerpc64/gen/swapcontext.S
RevisionDateAuthorComments
 1.5  13-Aug-2014  joerg [] -> ()
 1.4  12-Sep-2012  manu setcontext() used to be incompatible with -lpthread since it affected
the TLS pointer, therefore wrecking the pthread environement.

Some ports had _UC_TLSBASE flag or equivalent (_UC_UNIQUE on alpha)
that controlled whether setcontext() would change the TLS pointer.
This change let libpthread override setcontext() with its own version
that unsets _UC_TLSBASE, enabling safe usage of setcontext() with
-lpthread.

We also have the following required changes here:
- rename alpha's _UC_UNIQUE into _UC_TLSBASE
- add _UC_TLSBASE definition in header file for all ports
(powerpc, sh3, sparc and sparc64 lack the implementation for now)
- introduce a libc stub that can be overriden for setcontext()
- modify MD libcs swapcontext() implementations so that they use the
setcontext() libc stub instead of doing a plain system call.

While we are there:
- document various MD _UC_* flags in header file
- add libc and libpthread tests for swapcontext() behavior
(hopefully helpful to spot MD problems introduced with this change)

Future work:
- Deciding whether kernel support or _UC_TLSBASE should be added for
powerpc, sh3, sparc and sparc64 is left to portmasters
sparc64

Approved by core@
 1.3  28-Apr-2008  martin branches: 1.3.4; 1.3.8;
Remove clause 3 and 4 from TNF licenses
 1.2  05-Jul-2006  ross branches: 1.2.18;
revise for ppc64
 1.1  01-Jul-2006  ross ppc64 build framework first pass
 1.2.18.1  18-May-2008  yamt sync with head.
 1.3.8.2  28-Apr-2008  martin Remove clause 3 and 4 from TNF licenses
 1.3.8.1  28-Apr-2008  martin file swapcontext.S was added on branch christos-time_t on 2008-04-28 20:22:58 +0000
 1.3.4.1  30-Oct-2012  yamt sync with head

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