Hi Eric, On Fri, 8 Feb 2019, Eric Sunshine wrote:
> On Thu, Feb 7, 2019 at 5:46 AM Johannes Schindelin via GitGitGadget > <[email protected]> wrote: > > We cannot rely on `uname -m` in Git for Windows' SDK to tell us what > > architecture we are compiling for, as we can compile both 32-bit and > > 64-bit `git.exe` from a 64-bit SDK, but the `uname -m` in that SDK will > > always report `x86_64`. > > > > So let's go back to our original design. And make it explicitly > > Windows-specific. > > b22894049f (version --build-options: also report host CPU, 2017-12-15) > took this sort of case into consideration by introducing Makefile > variable HOST_CPU (which takes precedence over `uname -m`), with the > intention that, when cross-compiling, your build environment should > (somehow) set HOST_CPU to the canonical name of the CPU on which the > built Git will run (for instance, "x86_64" or "i686"). It would be > nice to employ this mechanism to solve this issue rather than > (re-)introducing a manually-maintained list of CPU names. Heh, this is also manually-maintained, but I agree that it is cleaner. > Can you say a few words (here in the email thread) about how the Git > for Windows SDK is instructed to build for one architecture or the > other? To cross-compile a 32-bit Git in a 64-bit Git for Windows SDK, use this incantation: MSYSTEM=MINGW32 PATH=/mingw32/bin:$PATH make > With such information, perhaps we can figure out how to get the build > environment itself to set HOST_CPU automatically so we don't have to > resort to and worry about maintenance costs of a hard-coded CPU name > list. Indeed, we can set HOST_CPU in the same conditionals as prefix (which is /mingw32 for 32-bit and /mingw64 for 64-bit) in config.mak.uname. Patch incoming, Dscho > > Signed-off-by: Johannes Schindelin <[email protected]> > > --- > > diff --git a/compat/mingw.h b/compat/mingw.h > > @@ -6,6 +6,25 @@ typedef _sigset_t sigset_t; > > +#ifdef __MINGW64_VERSION_MAJOR > > +/* > > + * In Git for Windows, we cannot rely on `uname -m` to report the correct > > + * architecture: /usr/bin/uname.exe will report the architecture with > > which the > > + * current MSYS2 runtime was built, not the architecture for which we are > > + * currently compiling (both 32-bit and 64-bit `git.exe` is built in the > > 64-bit > > + * Git for Windows SDK). > > + */ > > +#undef GIT_HOST_CPU > > +/* This was figured out by looking at `cpp -dM </dev/null`'s output */ > > +#if defined(__x86_64__) > > +#define GIT_HOST_CPU "x86_64" > > +#elif defined(__i686__) > > +#define GIT_HOST_CPU "i686" > > +#else > > +#error "Unknown architecture" > > +#endif > > +#endif >
