how to build the "dex2oat" for the target device?

[Abe Skolnik]

Dear all,

I can easily enough build "dex2oat" for the _host_ [ia32 executable], but I
can`t seem to figure out how to make AOSP build the "dex2oat" for the
_target_ device, e.g. a 32-bit ARM or AArch64 executable. I`ve already
checked on an Android 5.1-or-so device to see that there is such a thing,
and it seems that there _is_.

Please help.

Regards,

Abe

[Colin Cross]

On the latest AOSP:
$ source build/envsetup.sh
$ lunch aosp_arm64-eng
$ make -j32 dex2oat
[100% 3695/3695] Install: out/target/product/generic_arm64/system/bin/dex2oat
$ file out/target/product/generic_arm64/system/bin/dex2oat
out/target/product/generic_arm64/system/bin/dex2oat: ELF 32-bit LSB
shared object, ARM, EABI5 version 1 (SYSV), dynamically linked (uses
shared libs), BuildID[md5/uuid]=b7527da9a417d791c1282ba8444cb8fd,
stripped

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[Abe Skolnik]

Thanks, Colin.

Yes, I could have sworn it used to be that "easy"/"simple", but I recently noticed that my builds had the host "dex2oat" but not the target.

I recently found that asking GYP to build "droid" gave me the target "dex2oat".

Can anybody please explain why the target "dex2oat" is 32-bit [as judged by the "file" utility] even though I asked for AArch64?  [similarly, as you can see when Colin specified "aosp_arm64-eng"]

-- Abe

[Colin Cross]

I noticed that too. The decision is made here:
https://android.googlesource.com/platform/art/+/master/dex2oat/Android.mk#33

For 64-bit only devices it uses a 64-bit dex2oat, for mixed
64-bit/32-bit (like aosp_arm64-eng) and 32-bit only devices it uses
32-bit dex2oat. The 32-bit version is capable of compiling for
aarch32 or aarch64, it is an implementation detail that it is itself
compiled for aarch32, one that may change in the future.

[Abe Skolnik]

Thanks again, Colin!  You da` man!  ;-)

Is there any known way to force "dex2opt" [and the libraries upon which it depends] to be built purely 64-bit without hacking the makefiles and/or GYPfiles?

-- Abe

[Colin Cross]

No, you would have to modify art/dex2oat/Android.mk.