On Tue, 2 Feb 2021 19:23:16 GMT, Bernhard Urban-Forster <bur...@openjdk.org> wrote:
>> src/hotspot/os/posix/signals_posix.cpp line 1297: >> >>> 1295: kern_return_t kr; >>> 1296: kr = task_set_exception_ports(mach_task_self(), >>> 1297: EXC_MASK_BAD_ACCESS | >>> EXC_MASK_BAD_INSTRUCTION | EXC_MASK_ARITHMETIC, >> >> Could someone elaborate on why we need to add `EXC_MASK_BAD_INSTRUCTION` to >> the mask here? > > See comment above about `gdb`, the same applies to `lldb` today. The AArch64 > backend uses `SIGILL` (~= `EXC_MASK_BAD_INSTRUCTION`) to initiate a > deoptimization. Without this change you cannot continue debugging once you > the debuggee receives `SIGILL`. This wasn't needed before as x86 doesn't use > `SIGILL`. Part of the comment said `This work-around is not necessary for 10.5+, as CrashReporter no longer intercedes on caught fatal signals.` so I thought it was no longer needed, but it sounds like the part about `gdb` still applies then. We should update the comment to just say the `gdb` relevant part perhaps (and evaluate which of the EXC_MASK_BAD_ACCESS | EXC_MASK_BAD_INSTRUCTION | EXC_MASK_ARITHMETIC) we actually need for gdb: `// gdb installs both standard BSD signal handlers, and mach exception` `// handlers. By replacing the existing task exception handler, we disable gdb's mach` `// exception handling, while leaving the standard BSD signal handlers functional.` Do you know if this also apply to `lldb` or is it `gdb` only specific? How do you run `gdb` on macOS nowadays anyhow? ------------- PR: https://git.openjdk.java.net/jdk/pull/2200
