On Thu, 2007-10-11 at 22:26 +0300, Blue Swirl wrote: > On 10/10/07, Fabrice Bellard <[EMAIL PROTECTED]> wrote: > > Thiemo Seufer wrote: > > > Fabrice Bellard wrote: > > >> J. Mayer wrote: > > >>> Following the patches done for elfload32, it appeared to me that there > > >>> were still problems that would prevent 32 bits executables to run on 64 > > >>> bits target in linux user mode emulation. > > >>> [...] > > >> Are you sure it is a good idea to try to add 32 bit executable support > > >> to a > > >> 64 bit target ? In the end you will need to write a 64 bit to 32 bit > > >> linux > > >> syscall converter which would mean duplicating all the linux-user code of > > >> the corresponding 32 bit target (think of ioctls with strutures, signals > > >> frames, etc...). > > > > > > I would think this feature will be limited to platforms which can handle > > > 32bit and 64bit binaries with a single personality. > > > > I am not sure it is a common case ! > > > > However, I suggest to emulate a 32 bit user linux system with a 64 bit > > guest CPU running in 32 bit compatibily mode. It would be useful to test > > 64 bit CPUs in 32 bit compatibility mode. The only required modification > > in linux user is to rename target_ulong so that it can have a different > > size of the CPU word default size. > > I made a patch to rename target_ulong/long to abi_ulong/long and also > add a new emulator target that uses the 32 bit ABI with 64 bit CPU. > > Some Sparc32 binaries run, others don't, possibly indicating bugs in > the Sparc64 emulation! > > The patch is quite large because of the renaming, but this shouldn't > have effect to any other target. Any comments?
Great ! The patch seems safe, at first look, then I noticed a few things that are not correct or may be improved: * In linux-user/main.c: PowerPC DCR access should keep using target_ulong. This is a hardware bus, not an ABI dependent stuff. If a 32 bits cast is needed, it would be done in the micro-ops that handle the DCR bus accesses. * in linux-user/qemu.h: why is there still a OVERRIDE_ELF_CLASS variable, when checking TARGET_ABI32 should be sufficient ? It seems to me that having 2 defines which are, in fact, synonymous may be a source of confusion. * in configure: you also added a sparc64-softmmu target, which seems not related with this particular patch. * in configure: why add a specific TARGET_ABI32_DIR variable for that case ? It seems to me that a TARGET_ABI_DIR variable could be useful for all targets. Let me give an example: I want to add a ppcemb-linux-user target, emulating a PowerPC 32 with 64 bits registers and SIMD extensions but I don't want to duplicate the linux-user/ppc subdirectory. Having a TARGET_ABI_DIR available for all targets would solve my problem. In fact, even ppc and ppc64 could be merged... As you need this feature in your case, I think it would be a good idea to add it for all targets. And then, the kludge in Makefile.target could be replaced by: -CPPFLAGS+=-I$(SRC_PATH)/linux-user -I $(SRC_PATH)/linux-user/$(TARGET_ARCH) +CPPFLAGS+=-I$(SRC_PATH)/linux-user -I $(SRC_PATH)/linux-user/$(TARGET_ABI_DIR) which is simpler and easier to understand, imho. -- J. Mayer <[EMAIL PROTECTED]> Never organized
