问题一：在32位Ubuntu 12.04上编译Android4.0.4源码时，出现了关于emulator的错误，关键是其Makefile里的-m64参数，将其用-m32代替即可，错误提示如下：
ERROR: prebuilts/tools/gcc-sdk/../../gcc/linux-x86/host/x86_64-linux-glibc2.7-4.6/bin/x86_64-linux-gcc only run on 64-bit linux
make: *** [out/host/linux-x86/obj/STATIC_LIBRARIES/emulator64-target-arm_intermediates/tcg/tcg.o] Error 1
涉及需要改的文件如下：
external/qemu/Makefile.target
external/qemu/Makefile.common
问题二：编译时出现如下提示：
target Dex: core
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
make: *** [out/target/common/obj/JAVA_LIBRARIES/core_intermediates/noproguard.classes-with-local.dex] Error 1
查找build/core/definitions.mk文件发现如下内容：
#TODO: use a smaller -Xmx value for most libraries;
# only core.jar and framework.jar need a heap this big.
# Avoid the memory arguments on Windows, dx fails to load for some reason with them.
define transform-classes.jar-to-dex
@echo "target Dex: $(PRIVATE_MODULE)"
@mkdir -p $(dir $@)
$(hide) $(DX) \
$(if $(findstring windows,$(HOST_OS)),,-JXms16M -JXmx2048M) \
--dex --output=$@ \
$(incremental_dex) \
$(if $(NO_OPTIMIZE_DX), \
--no-optimize) \
$(if $(GENERATE_DEX_DEBUG), \
--debug --verbose \
--dump-to=$(@:.dex=.lst) \
--dump-width=1000) \
$(PRIVATE_DX_FLAGS) \
$<
endef
由于我的电脑只有2GB的内容，那么上面的2048M肯定满足不了，因为linux分配时还需分配给内核内存，故将该参数调小为1024M。
继续编译还会出现一些关于emulator的错误，而查阅了google官方资料，说是要在64bit系统上编译，换成64位的后，没出现什么错误，编译一切正常。