1------------------------------------------------------------------- 2Guide to multiple architecture support 3------------------------------------------------------------------- 4 5What is achieved 6~~~~~~~~~~~~~~~~ 7Valgrind supports systems where binaries for more than one 8architecture can be run. The current arrangements build: 9 10- single-arch support on x86 and ppc32 systems 11- dual-arch support on amd64 and ppc64 systems 12 13To support this the valgrind build system can now build multiple 14versions of the coregrind library and of VEX, and then build and link 15multiple versions of each tool. 16 17A central notion is that of 'primary' vs 'secondary' platforms. The 18system is built in its entirety for the primary platform, including 19performance and regression suites and all auxiliary programs. For 20dual-arch systems, the primary platform is amd64 and ppc64 21respectively. 22 23On dual-arch systems, there is a 'secondary' target - x86 and ppc32 24respectively. The tools are built again for the secondary target, and 25the 'valgrind' launcher program can handle executables for either the 26primary or secondary target. However, the regression and performance 27tests and everything else is not rebuilt for the secondary target. 28 29On single-arch systems, there is no secondary target. 30 31 32How the build system does that 33~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 34The keys to understanding this are in: 35 36- configure.in 37- Makefile.flags.am 38- <tool>/tests/Makefile.am 39- <tool>/tests/<arch>/Makefile.am 40- perf/Makefile.am 41 42The configure script inspects the CPU. It then sets 43 44 VGCONF_PLATFORM_PRI_CAPS to be the primary target 45 VGCONF_PLATFORM_SEC_CAPS to be the secondary target, if any 46 47It also sets one (single-arch build) or two (dual-arch build) of 48the following: 49 50 VGCONF_PLATFORMS_INCLUDE_X86_LINUX 51 VGCONF_PLATFORMS_INCLUDE_AMD64_LINUX 52 VGCONF_PLATFORMS_INCLUDE_PPC32_LINUX 53 VGCONF_PLATFORMS_INCLUDE_PPC64_LINUX 54 ... 55 56On an amd64 system both VGCONF_PLATFORMS_INCLUDE_X86_LINUX and 57VGCONF_PLATFORMS_INCLUDE_AMD64_LINUX will be true so that two versions of 58all the tools will be built. Similarly on a ppc64 system both 59VGCONF_PLATFORMS_INCLUDE_PPC32_LINUX and 60VGCONF_PLATFORMS_INCLUDE_PPC64_LINUX will be defined (unless 61--enable-only32bit or --enable-only64bit is used). For the amd64 example, 62 the coregrind libraries will be named: 63 64 libcoregrind_x86_linux.a 65 libcoregrind_amd64_linux.a 66 67and the VEX libraries: 68 69 libvex_x86_linux.a 70 libvex_amd64_linux.a 71 72Each tool will then be built twice, along with any preload library 73for the tool and the core preload libraries. At install time one 74subdirectory will be created in the valgrind library directory for 75each supported platforms and the tools and shared objects will be 76installed in the appropriate place. On amd64 the result will be: 77 78 <prefix>/lib/valgrind 79 <prefix>/lib/valgrind/default.supp 80 <prefix>/lib/valgrind/glibc-2.4.supp 81 <prefix>/lib/valgrind/hp2ps 82 <prefix>/lib/valgrind/amd64-linux 83 <prefix>/lib/valgrind/amd64-linux/vgpreload_core.so 84 <prefix>/lib/valgrind/amd64-linux/vgpreload_massif.so 85 <prefix>/lib/valgrind/amd64-linux/cachegrind 86 <prefix>/lib/valgrind/amd64-linux/memcheck 87 <prefix>/lib/valgrind/amd64-linux/helgrind 88 <prefix>/lib/valgrind/amd64-linux/massif 89 <prefix>/lib/valgrind/amd64-linux/vgpreload_memcheck.so 90 <prefix>/lib/valgrind/amd64-linux/lackey 91 <prefix>/lib/valgrind/amd64-linux/none 92 <prefix>/lib/valgrind/amd64-linux/vgpreload_helgrind.so 93 <prefix>/lib/valgrind/xfree-3.supp 94 <prefix>/lib/valgrind/x86-linux 95 <prefix>/lib/valgrind/x86-linux/vgpreload_core.so 96 <prefix>/lib/valgrind/x86-linux/vgpreload_massif.so 97 <prefix>/lib/valgrind/x86-linux/cachegrind 98 <prefix>/lib/valgrind/x86-linux/memcheck 99 <prefix>/lib/valgrind/x86-linux/helgrind 100 <prefix>/lib/valgrind/x86-linux/massif 101 <prefix>/lib/valgrind/x86-linux/vgpreload_memcheck.so 102 <prefix>/lib/valgrind/x86-linux/lackey 103 <prefix>/lib/valgrind/x86-linux/none 104 <prefix>/lib/valgrind/x86-linux/vgpreload_helgrind.so 105 <prefix>/lib/valgrind/glibc-2.3.supp 106 <prefix>/lib/valgrind/xfree-4.supp 107 <prefix>/lib/valgrind/glibc-2.2.supp 108 109The launcher program (ie the valgrind binary itself) is always built 110as a program for the primary target (so a 64 bit program on amd64 and 111ppc64) but will peek at the program which it is being asked to run and 112decide which of the possible tools to run taking both the requested 113tool and the format of the program being run into account. 114 115Because the execv system call is now routed back through the launcher 116it is also possible to exec an x86 program from an amd64 program and 117vice versa. Ditto ppc32 and ppc64. 118 119 120Rules for Makefile.am hacking 121~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 122In places where compilation should happen twice (on a dual-arch 123system), the decision about which directories and flags to use is 124guarded by the VGCONF_PLATFORMS_INCLUDE_* symbols. 125 126But there are also places where building must only happen once, 127for the primary architecture. These places are (at least): 128 129* the launcher, valgrind.c 130* all the architecture-independent regression tests 131* the performance tests 132* optionally, auxiliary programs like hp2ps and valgrind-listener 133 134In order to do that, we need to know what flags to use to build for 135the primary target, and in particular whether to hand -m32 or -m64 to 136gcc. This is where Makefile.flags.am comes in. 137 138At the bottom of that file are defined AM_CPPFLAGS_PRI, AM_CFLAGS_PRI 139and AM_CCASFLAGS_PRI that must be used for compiling for the primary 140architecture. For example, look in coregrind/Makefile.am, and you 141will see these flag-sets being used to build the launcher (valgrind). 142 143Also at the bottom of Makefile.flags.am, AM_FLAG_M3264_PRI is defined. 144This gives the -m32/-m64 flag needed to build for the primary target. 145That flag is also contained within AM_CFLAGS_PRI -- AM_FLAG_M3264_PRI 146merely facilitates getting hold of it without the surrounding gunk. 147 148This leads to the final complication: building the regression tests. 149Most of them are architecture-neutral and so should be built for the 150primary target. The /test/ Makefile.am's duly include 151AM_FLAG_M3264_PRI in the compilation invocations, and you should 152ensure you preserve that when adding more tests. 153 154However, there are some arch-specific test directories (eg, 155none/tests/ppc32, etc). In each of these, we implicitly 'know' 156whether -m32 or -m64 is the right thing to specify. So instead of 157messing with AM_FLAG_M3264_PRI, these directories merely specific 158@FLAG_M32@ or @FLAG_M64@ directly. (These two symbols are also 159automagically set up by configure.in. Do not use -m32 and -m64 160directly - older compilers barf on them). Another reason not to 161use -m32 and -m64 directly is that they are called -maix32 and 162-maix64 on AIX; once again this is taken care of properly if you 163use @FLAG_M32@ and @FLAG_M64@ instead. 164