On 27/02/2015 11:25 AM, Andrew Hughes wrote:
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<trimming>
On 26/02/2015 12:31 PM, David Holmes wrote:
On 26/02/2015 2:57 AM, Andrew Hughes wrote:
These are the revised versions of the webrevs:
http://cr.openjdk.java.net/~andrew/rh1191652/webrev.02/root/
http://cr.openjdk.java.net/~andrew/rh1191652/webrev.02/jdk/
http://cr.openjdk.java.net/~andrew/rh1191652/webrev.02/hotspot/
(HotSpot is unchanged, dropped the sound changes from JDK)
Ok if I push the jdk and root parts then? I think someone on the Oracle
HS team (David?) needs to push the HotSpot bit.
Best to push it all together I think, which I can do through the hs-rt
forest. But first I need to see where things settled with all this :) I
was quite confused by some of the initial suggestions. Will try to get
to this today.
Well, I'd push it all myself if there weren't still restrictions on pushing
to HotSpot...
I'm still very confused by these changes and have trouble tracking the
values of the various "arch" related variables. If I follow this right
presently the only distinction between ppc64 and ppc64le is the value of
OPENJDK_TARGET_CPU_ENDIAN. In particular they both use ppc64 as the
hotspot LIBARCH value and ppc as the ARCH value. (Aside: so ARCH/ppc64
is either unused or only used by a hotspot-only build?)
The desired change is that the top-level architecture (VAR_CPU which
becomes OPENJDK_TARGET_CPU) should now be ppc64le not ppc64, but that
for hotspot the only difference is LIBARCH becomes ppc64le. So to
achieve this hotspot-spec.gmk switches ARCH to be ppc64 instead of the
current ppc; and then hotspot's def.make uses that combined with being
lttle-endian to reset the LIBARCH to ppc64le.
From ppc64le. Without the override in hotspot-spec.gmk, the HotSpot build
will get called with ARCH=ppc64le and fail, because make/defs.make will
set SRCARCH to x86
No, ARCH comes from $(OPENJDK_TARGET_CPU_ARCH) which comes from
$VAR_CPU_ARCH which is still ppc, not ppc64le. So SRCARCH will be set to
ppc as per current code. Then BUILDARCH will check LP64 and so become
ppc64. Then you can check endian-ness to define LIBARCH to ppc64le.
This all seems very convoluted! Why can you not simply check the value
of BUILD_ARCH for ppc64 and then check the endianess to redefine
LIBARCH? That way you don't need to change ARCH as set by hotspot-spec.gmk.
How is this different to what we are doing?
Because it doesn't require the switcheroo in the hotspot-spec.gmk.in file
+ # Override LIBARCH for ppc64le
+ ifeq ($(ARCH), ppc64)
+ ifeq ($(OPENJDK_TARGET_CPU_ENDIAN), little)
+ LIBARCH = ppc64le
+ endif
+ endif
Right there; we're checking the endianness to redefine LIBARCH.
Yes but you can do it based on the value of LIBARCH rather than a
modified ARCH.
Does "uname -m" return ppc64le ? I'm unclear whether either your
proposal or mine actually works correctly for a hotspot-only build. But
maybe we just don't care about builds not done via configure any more.
It does. Different logic is employed for a configure build (which
sets various variables, including ARCH, in hotspot-spec.gmk) and
a HotSpot-only build which just use makefiles. If ARCH is not set
when we get to the HotSpot build, as in the latter, this block
in make/linux/makefiles/defs.make is used:
ifndef ARCH
ARCH := $(shell uname -m)
# Fold little endian PowerPC64 into big-endian (if ARCH is set in
# hotspot-spec.gmk, this will be done by the configure script).
ifeq ($(ARCH),ppc64le)
ARCH := ppc64
endif
endif
This was added as part of:
8036767: PPC64: Support for little endian execution model
I don't know if I already had this conversation but it strikes me as
really bizarre that the PPC64 port uses two different ARCH values
depending on whether it is a configure-based build or not! ???
That aside if ARCH == ppc64 from uname then:
- SRCARCH = ARCH/ppc64 = ppc
- BUILDARCH = ppc64
and so the same fix as above would work for this case.
so our addition to hotspot-spec.gmk is just to do the same as this
block for configure builds.
It was unneeded before because configure would just set the arch
to ppc64 for the entire build, not just HotSpot.
AFAICS it set it to ppc not ppc64.
David
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Thanks,
David
Given the LIBARCH switcheroo that happens in hotspot/make/def.make, why
bother also doing the switcheroo in
<top>/common/autoconf/hotspot-spec.gmk.in when you could just do
everything in hotspot/make/defs
David
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Thanks,
