Add an experimental build-only continuous cross compile build for Lin…

…ux Aarch64

PiperOrigin-RevId: 613624879

.bazelrc

@@ -282,6 +282,46 @@ build:rbe_linux_cuda12.3_nvcc_py3.12 --python_path="/usr/local/bin/python3.12"
 build:tensorflow_testing_rbe --project_id=tensorflow-testing
 common:tensorflow_testing_rbe_linux --remote_instance_name=projects/tensorflow-testing/instances/default_instance
 build:tensorflow_testing_rbe_linux --config=tensorflow_testing_rbe
+
+# START CROSS-COMPILE CONFIGS
+
+# Set execution platform to Linux x86
+# Note: Lot of the "host_" flags such as "host_cpu" and "host_crosstool_top"
+# flags seem to be actually used to specify the execution platform details. It
+# seems it is this way because these flags are old and predate the distinction
+# between host and execution platform.
+build:cross_compile_base --host_cpu=k8
+build:cross_compile_base --host_crosstool_top=@xla//tools/toolchains/cross_compile/cc:cross_compile_toolchain_suite
+build:cross_compile_base --extra_execution_platforms=@xla//tools/toolchains/cross_compile/config:linux_x86_64
+
+# START LINUX AARCH64 CROSS-COMPILE CONFIGS
+build:cross_compile_linux_arm64 --config=cross_compile_base
+
+# Set the target CPU to Aarch64
+build:cross_compile_linux_arm64 --platforms=@xla//tools/toolchains/cross_compile/config:linux_aarch64
+build:cross_compile_linux_arm64 --cpu=aarch64
+build:cross_compile_linux_arm64 --crosstool_top=@xla//tools/toolchains/cross_compile/cc:cross_compile_toolchain_suite
+
+build:rbe_cross_compile_base --config=rbe
+# JAX depends on some local Python headers that are configured as Genrule. They
+# are present on the local host machine but not on the remote execution machine,
+# leading to build failures. To resolve the issue, the following line is added
+# to make sure all Genrule targets are excuted locally.
+build:rbe_cross_compile_base --strategy=Genrule=standalone
+# Due to the above strategy, all Genrule commands are executed locally, but the
+# following actions invoke tools (E.g `flatc`, `llvm-tblgen`, etc.) that are
+# only executabe on the RBE (x86) machine, so the strategy_regexp options are
+# added to override and run the actions using remote strategy.
+build:rbe_cross_compile_base --strategy_regexp='Generating code from table.*=remote'
+build:rbe_cross_compile_base --strategy_regexp='Generating flatbuffer files.*=remote'
+build:rbe_cross_compile_base --strategy_regexp='Executing genrule @llvm-project.*=remote'
+
+# RBE cross-compile configs for Linux Aarch64
+build:rbe_cross_compile_linux_arm64 --config=cross_compile_linux_arm64
+build:rbe_cross_compile_linux_arm64 --config=rbe_cross_compile_base
+# END LINUX AARCH64 CROSS-COMPILE CONFIGS
+# END CROSS-COMPILE CONFIGS
+
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