On Thu, Jul 23, 2020 at 11:17 AM Thomas Gleixner <[email protected]> wrote: > > Thomas Gleixner <[email protected]> writes: > > Nick Desaulniers <[email protected]> writes: > > > > I'm glad I looked myself at this. > > > >> We also don't want to swap the use of "=q" with "=r". For 64b, it > >> doesn't matter. For 32b, it's possible that a 32b register without a 8b > >> lower alias (i.e. ESI, EDI, EBP) is selected which the assembler will > >> then reject. > > > > The above is really garbage. > > > > We don't want? It's simply not possible to do so, because ... > > > > 64b,32b,8b. For heavens sake is it too much asked to write a changelog > > with understandable wording instead of ambiguous abbreviations? > > > > There is no maximum character limit for changelogs. > > Gah. Hit send too fast. > > >> With this, Clang can finally build an i386 defconfig. > > With what? I can't find anything which explains the solution at the > conceptual level. Sigh. >
Hi, I have applied this patch-series v3 but some basics of "i386" usage are not clear to me when I wanted to test it and give some feedback. [1] is the original place in CBL where this was reported and I have commented on this. Beyond some old cruft in i386_defconfig like non-existent "CONFIG_CRYPTO_AES_586" I have some fundamental questions: What means "ARCH=i386" and where it is used (for)? I can do: $ ARCH=x86 make V=1 -j3 $MAKE_OPTS i386_defconfig $ make V=1 -j3 $MAKE_OPTS i386_defconfig ...which results in the same .config. Whereas when I do: $ ARCH=i386 make V=1 -j3 $MAKE_OPTS i386_defconfig ...drops CONFIG_64BIT line entirely. But "# CONFIG_64BIT is not set" is explicitly set in arch/x86/configs/i386_defconfig but gets dropped. Unsure if above is the same like: $ ARCH=i386 make V=1 -j3 $MAKE_OPTS defconfig When generating via "make ... i386_defconfig" modern gcc-9 and and a snapshot version of clang-11 build both with: $ ARCH=x86 make V=1 -j3 $MAKE_OPTS ... -march=i686 -mtune=generic ... Checking generated .config reveals: CONFIG_M686=y So, I guess modern compilers do at least support "i686" as lowest CPU? Doing some grep+ping: $ git grep "ARCH=i386" Documentation/kbuild/headers_install.rst: make headers_install ARCH=i386 INSTALL_HDR_PATH=/usr tools/testing/ktest/examples/crosstests.conf:MAKE_CMD = make ARCH=i386 tools/testing/ktest/sample.conf:#MAKE_CMD = CC=i386-gcc AS=i386-as make ARCH=i386 i386-gcc / i386-as - someone uses that? Again my question (I did not do a diff): $ make headers_install ARCH=i386 INSTALL_HDR_PATH=/usr $ make headers_install ARCH=x86 INSTALL_HDR_PATH=/usr ...should generate the same? To come back to "i386" again: $ git grep i386 | grep ARCH ...reveals in top-level Makefile [2]: 376: # Additional ARCH settings for x86 377: ifeq ($(ARCH),i386) 378: SRCARCH := x86 For me this means: ARCH=i386 make ... ARCH=x86 make ... ...should result in the same .config, but for what reason CONFIG_64BIT is dropped when "ARCH=i386" is used. Coming to a conclusion: Nick D. says: > I usually test with make ... i386_defconfig. Can you enlighten a bit? Of course, I can send a patch to remove the "CONFIG_CRYPTO_AES_586=y" line from i386_defconfig. Thanks. Regards, - Sedat - [1] https://github.com/ClangBuiltLinux/linux/issues/194 [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Makefile#n376
