I hit the same problem trying to install 5.14.0-RC1 with perlbrew on some *OLD* Linux distros... I installed 5.12.3 with no trouble, though I believe this io/eintr.t file came in 5.13. I wasn't sure where I could find minimum system requirements, so I apologize if I shouldn't have bothered with this, but I also wasn't sure where the breakdown was so I thought perhaps someone would be interested. It's probably my ancient kernels: Linux 2.6.5-1.358 #1 Sat May 8 09:04:50 EDT 2004 i686 i686 i386 GNU/Linux Linux 2.6.10-1.771_FC2 #1 Mon Mar 28 00:50:14 EST 2005 i686 i686 i386 GNU/Linux gcc (GCC) 3.3.3 20040412 (Red Hat Linux 3.3.3-7) (2003) glibc-2.3.3 Fedora Core release 2 (Tettnang) I skipped the test and everything seems ok (no pun intended). Let me know if you'd like any more information, or please ignore this if this system is too old... I can't imagine anybody cares. The next oldest machine I could try it on was: Linux 2.6.12-1.1381_FC3smp #1 SMP Fri Oct 21 04:03:26 EDT 2005 i686 i686 i386 GNU/Linux Fedora Core release 3 (Heidelberg) glibc-2.3.6 gcc (GCC) 3.4.4 20050721 (Red Hat 3.4.4-2) (2004) and I had no problems.