diff -up glibc-2.34/sysdeps/unix/sysv/linux/Makefile.bero~ glibc-2.34/sysdeps/unix/sysv/linux/Makefile
--- glibc-2.34/sysdeps/unix/sysv/linux/Makefile.bero~	2021-09-22 21:04:37.378000000 +0000
+++ glibc-2.34/sysdeps/unix/sysv/linux/Makefile	2021-09-22 21:06:55.990000000 +0000
@@ -76,6 +76,10 @@ CFLAGS-open_by_handle_at.c = -fexception
 CFLAGS-sync_file_range.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-pselect32.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-tst-writev.c += "-DARTIFICIAL_LIMIT=(0x80000000-sysconf(_SC_PAGESIZE))"
+# select.c is broken on i686 with -O3. Appears to be a compiler bug.
+# "error: bp cannot be used in 'asm' here" where there's no asm code
+# anywhere near.
+CFLAGS-select.c = -O2
 
 sysdep_headers += sys/mount.h sys/acct.h \
 		  sys/klog.h \