Ported build system and source to macOS arm64 by peturingi · Pull Request #10 · openwall/yescrypt

peturingi · 2026-03-23T16:03:06Z

Ported to macOS by solving the following problems:

Makefile assumed Linux (GCC, -lrt, -fopenmp). Modified to detects macOS (Darwin kernel) via uname -s then set compiler/linker flags accordingly. Linux flags are unchanged.

sched_setscheduler() does not exist on macOS. Guarded with #ifndef __APPLE__ since it is only a non-essential SCHED_RR optimization for benchmarking as root.

Apple Clang has three issues that prevent compilation:

-fopenmp is not supported by Apple Clang. Used -Xpreprocessor -fopenmp with Homebrew libomp headers and library instead.
-lrt does not exist on macOS. librt provides clock_gettime() and POSIX timers on Linux; macOS includes these in libSystem.
-s (strip at link time) is obsolete on macOS ld.

Should you choose to accept this PR, please mind documenting the dependency on libomp for those who want to build on macOS.

The upstream Makefile assumes Linux (GCC, -lrt, -fopenmp). On macOS with Apple Clang, three issues prevent compilation: 1. -fopenmp is not supported by Apple Clang. Use -Xpreprocessor -fopenmp with Homebrew libomp headers and library instead. 2. -lrt does not exist on macOS. librt provides clock_gettime() and POSIX timers on Linux; macOS includes these in libSystem. 3. -s (strip at link time) is obsolete on macOS ld. The Makefile now detects Darwin via uname -s and sets compiler/linker flags accordingly. Linux flags are unchanged. Additionally, userom.c calls sched_setscheduler() which does not exist on macOS. Guarded with #ifndef __APPLE__ since it is only a non-essential SCHED_RR optimization for benchmarking as root.

peturingi · 2026-03-23T16:04:09Z

 # SUCH DAMAGE.

-CC = gcc
+CC = cc


NOTE: I did not guard this. Problem?

The specific flags we use assume GCC on Linux and apparently clang on macOS? If so, I guess you need to move the CC = line to inside the ifeq/else, and the LD line to after endif.

Also, e.g. on Solaris cc may be Sun's compiler, which does not recognize gcc options, yet I fixed this Makefile to work for Solaris just recently... except that I also broke it on SPARC later by adding -march=native, which gcc for that arch does not recognize.

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Pull request overview

Ports the build and benchmarking utilities to support macOS (Darwin) on arm64 by adjusting compiler/linker flags and guarding Linux-only scheduling optimizations.

Changes:

Add a macOS-specific Makefile branch that uses Homebrew libomp for OpenMP and removes Linux-only linker flags.
Guard the sched_setscheduler() SCHED_RR benchmarking optimization to avoid building/calling it on Apple platforms.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
`Makefile`	Adds Darwin detection and uses Homebrew `libomp` OpenMP flags; updates default compiler selection.
`userom.c`	Wraps `sched_setscheduler()` usage with `#ifndef __APPLE__` to compile on macOS.

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peturingi · 2026-05-01T00:28:18Z

Issues?

solardiz · 2026-05-01T04:55:26Z

@peturingi I'm sorry I'm in a bad lack of time lately. I do appreciate your contribution and your persistence. Thank you! I do intend to review this properly.

Note that we also have similar codebase in https://github.com/openwall/yespower so we could want to keep them in sync.

solardiz · 2026-05-01T04:56:25Z


 		unsigned long long count1 = count, count_restart = 0;

+#ifndef __APPLE__


Let's try #ifdef SCHED_RR.

We'll get #ifdef SCHED_RR via #11 now, and will then need to revisit the rest of changes in this PR.

solardiz

I requested some changes, but I also note that this requires GNU make, whereas before these changes the default make on Solaris could handle this Makefile as well. Not a big deal, because it's so common to have GNU make installed on Solaris as gmake and be using that. Still, this isn't strictly a portability improvement - it also hurts portability.

solardiz · 2026-05-02T23:03:16Z

 # SUCH DAMAGE.

-CC = gcc
+CC = cc


The specific flags we use assume GCC on Linux and apparently clang on macOS? If so, I guess you need to move the CC = line to inside the ifeq/else, and the LD line to after endif.

Also, e.g. on Solaris cc may be Sun's compiler, which does not recognize gcc options, yet I fixed this Makefile to work for Solaris just recently... except that I also broke it on SPARC later by adding -march=native, which gcc for that arch does not recognize.

solardiz · 2026-05-02T23:20:37Z

Note that the current build system here is just for testing and benchmarking, not for building production code.

Separately from this PR, we could want to implement a proper build system that would build a library and tools and test suite for the library and the tools. For doing so, we could want to consider how passwdqc is built and decide whether we want to be similar or different here. Just thinking out loud, not a request.

Leont · 2026-05-17T01:08:19Z

-lrt does not exist on macOS. librt provides clock_gettime() and POSIX timers on Linux; macOS includes these in libSystem.

Since glibc 2.34 librt has been merged into libc so it's not necessary anymore on modern Linux (at least when using glibc), it still exists but as an empty library.

solardiz · 2026-06-15T19:03:36Z

Now that #11 is merged, what further changes do we want to make related to this PR? cc: @quadcpu

Regarding -s -lrt, I think we should drop -s, but I am unsure about dropping -lrt as glibc 2.34+ means RHEL 9+ and such, whereas 8 and even 7 are still in use (8 still maintained upstream, 7 is in "extended support" by RH and several downstreams).

quadcpu · 2026-06-15T19:24:59Z

@solardiz I know very little about macos or clang but gcc is ln'ed with cc which is clang compiler, and currently clang compiler works with something like

make check \
            CFLAGS="-Wall -O2 -fomit-frame-pointer -DSKIP_MEMZERO" \
            OMPFLAGS_MAYBE="" LDFLAGS=""

on https://github.com/openwall/yescrypt/actions/runs/27568978084/job/81500253260 though.

for -lrt got something like

  On -lrt: rather than deciding "drop vs. keep" globally, I'd make it conditional on the platform so we don't have to pick between old RHEL and macOS. Detect Darwin via uname -s and adjust the flags there,
  leaving the Linux path exactly as-is:

  LDFLAGS = -s $(OMPFLAGS_MAYBE)
  ifeq ($(shell uname -s),Darwin)
  # clock_gettime() is in libSystem; ld's -s is obsolete
  LDFLAGS = $(OMPFLAGS_MAYBE)
  else
  # -lrt is for userom's use of clock_gettime() (folded into libc in glibc 2.34+,
  # but still needed on pre-2.34 systems like RHEL 7/8)
  LDFLAGS += -lrt
  endif

  That keeps -lrt for RHEL 7/8 (and anything pre-glibc-2.34) while not breaking Darwin, and avoids a behavior change for existing Linux users. As @Leont noted, glibc 2.34+ keeps an empty librt around anyway,
  so -lrt stays harmless on RHEL 9+.

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solardiz mentioned this pull request Jun 13, 2026

Add MSVC build scripts & fix for MSVC #11

Merged


		unsigned long long count1 = count, count_restart = 0;

		#ifndef __APPLE__

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