fix gemm segfault

print exit signals on validation failure

validation/subprocess_utils.py

@@ -4,6 +4,8 @@ import pty
 import selectors
 import subprocess
 
+MAX_ERROR_OUTPUT_BYTES = 8192
+
 
 def _read_chunk(fd, treat_eio_as_eof=False):
     try:
@@ -16,6 +18,7 @@ def _read_chunk(fd, treat_eio_as_eof=False):
 
 def _stream_output(fd, process, reporter, treat_eio_as_eof=False):
     selector = selectors.DefaultSelector()
+    recent_output = bytearray()
 
     try:
         selector.register(fd, selectors.EVENT_READ)
@@ -31,12 +34,15 @@ def _stream_output(fd, process, reporter, treat_eio_as_eof=False):
                 reporter._clear()
                 os.write(1, data)
                 reporter._render()
+                recent_output.extend(data)
+                if len(recent_output) > MAX_ERROR_OUTPUT_BYTES:
+                    del recent_output[:-MAX_ERROR_OUTPUT_BYTES]
     finally:
         selector.close()
 
     return_code = process.wait()
     if return_code != 0:
-        raise subprocess.CalledProcessError(return_code, process.args)
+        raise subprocess.CalledProcessError(return_code, process.args, output=bytes(recent_output))
 
 
 def run_command_with_reporter(cmd, cwd=None, reporter=None):