add: build instructions for mac arm

Author: jimfangx

README.md

@@ -34,7 +34,7 @@ Also available for Arch users on the AUR: [https://aur.archlinux.org/packages/ri
 
 On macOS, you can use [Homebrew](http://brew.sh) to install the dependencies:
 
-    $ brew install python3 gawk gnu-sed make gmp mpfr libmpc isl zlib expat texinfo flock libslirp ncurses
+    $ brew install python3 gawk gnu-sed make gmp mpfr libmpc isl zlib expat texinfo flock libslirp ncurses ninja bison m4 wget
 
 When executing the instructions in this README, please use `gmake` instead of `make` to use the newly installed version of make.
 To build the glibc (Linux) on macOS, you will need to build within a case-sensitive file
@@ -111,6 +111,25 @@ This option only takes effect for the GNU toolchain.
 The toolchain has an option `--enable-strip` to control strip of host binaries,
 strip is disabled by default.
 
+### Installation (MacOS ARM)
+
+First, ensure you have cloned the toolchain repository in a case-sensitive volume. 
+
+Now source `macos.zsh` to setup the PATH variable so that the build scripts can use the tools from homebrew, which are needed to build the GNU toolchain.
+
+Then, run configure with your desired flags - For example:
+```
+./configure --prefix=/Volumes/case-sensitive/opt/riscv --with-arch=rv64gc_zifencei --with-abi=lp64d --enable-linux --disable-gdb
+```
+
+Then, raise the limit of open files. Run: `ulimit -n 65536`
+
+Builds on MacOS are highly specific to OS versions and the versions of the developer tools installed. We recommend running `make check-binutils` first, which will help surface a some of the more frequent build errors we've seen without having to start a full build.
+
+If `make check-binutils` errors, check the [following documentation](./macos-build.md) for a list of common errors when building on MacOS and their solutions.
+
+When `make check-binutils` finishes successfully, you run the build normally with `make` or `make linux`.
+
 ### Troubleshooting Build Problems
 
 Builds work best if installing into an empty directory.  If you build a

macos-build.md

@@ -0,0 +1,50 @@
+# MacOS Build Common Errors
+
+## fdopen macro redefinition error
+
+During `make check-binutils`, you may see an error like this:
+```bash
+In file included from /Volumes/case-sensitive/riscv-gnu-toolchain/binutils/zlib/zlib/zutil.c:10:
+In file included from /Volumes/case-sensitive/riscv-gnu-toolchain/binutils/zlib/zlib/gzguts.h:21:
+In file included from /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h:61:
+/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h:322:7: error: expected identifier or '('
+  322 | FILE    *fdopen(int, const char *) __DARWIN_ALIAS_STARTING(__MAC_10_6, __IPHONE_2_0, __DARWIN_ALIAS(fdopen));
+      |          ^
+/Volumes/case-sensitive/riscv-gnu-toolchain/binutils/zlib/zlib/zutil.h:147:33: note: expanded from macro 'fdopen'
+  147 | #        define fdopen(fd,mode) NULL /* No fdopen() */
+      |                                 ^
+/Library/Developer/CommandLineTools/usr/lib/clang/17/include/__stddef_null.h:26:16: note: expanded from macro 'NULL'
+   26 | #define NULL ((void*)0)
+      |                ^
+```
+
+Then, upate the `binutils` repository to the latest commit on the `gdb-17-branch`. The easiest way to do this is (in the `riscv-gnu-toolchain` folder):
+
+```bash
+rm -rf binutils
+git clone https://github.com/bminor/binutils-gdb binutils
+cd binutils
+git checkout gdb-17-branch
+cd ..
+```
+(The gdb-17-branch was last tested to be working on MacOS Tahoe 26.2 (25C56) on an M2 Max machine model A2779)
+
+
+## Bison/YACC related errors
+There may be missing files errors like this during `make`:
+```bash
+clang: error: no such file or directory: '/Volumes/case-sensitive/riscv-gnu-toolchain/binutils/binutils/sysinfo.c'
+clang: error: no input files
+gmake[3]: *** [Makefile:1897: sysinfo.o] Error 1
+gmake[3]: Leaving directory '/Volumes/case-sensitive/riscv-gnu-toolchain/build-binutils-newlib/binutils'
+```
+To fix this, you need to run some files manually through Bison in YACC mode:
+```bash
+cd binutils/binutils
+bison -y -o sysinfo.c sysinfo.y
+bison -y -d --defines=sysinfo.h -o sysinfo.c sysinfo.y
+bison -d --defines=arparse.h -o arparse.c arparse.y
+
+cd binutils/ld
+bison -d --defines=ldgram.h -o ldgram.c ldgram.y
+```

macos.zsh

@@ -0,0 +1,11 @@
+export PATH="/opt/homebrew/opt/bison/bin:$PATH"
+export PATH="/opt/homebrew/opt/gawk/libexec/gnubin:$PATH"
+export PATH="/opt/homebrew/opt/gnu-sed/libexec/gnubin:$PATH"
+export PATH="/opt/homebrew/opt/make/libexec/gnubin:$PATH"
+export PATH="/opt/homebrew/opt/expat/bin:$PATH"
+export PATH="opt/homebrew/opt/bison/bin:$PATH"
+export GNUMAKE="/opt/homebrew/opt/make/libexec/gnubin/make"
+export MAKE="/opt/homebrew/opt/make/libexec/gnubin/make"
+export PATH="/opt/homebrew/opt/m4:bin$PATH"
+alias gcc="/opt/homebrew/bin/gcc-15"
+alias gmp="opt/homebrew/Cellar/gmp/6.3.0/include/"