openat(AT_FDCWD, "/dev/ttyS0", O_RDWR|O_NOCTTY|O_NONBLOCK|O_CLOEXEC) = 27
ioctl(27, TIOCEXCL) = 0
ioctl(27, TCGETS, {B19200 -opost -isig -icanon -echo ...}) = 0
ioctl(27, TCGETS, {B19200 -opost -isig -icanon -echo ...}) = 0
ioctl(27, SNDCTL_TMR_START or TCSETS, {B19200 -opost -isig -icanon -echo ...}) = 0
ioctl(27, TCGETS, {B19200 -opost -isig -icanon -echo ...}) = 0
ioctl(27, TIOCMGET, [TIOCM_DTR|TIOCM_RTS|0x4000]) = 0
ioctl(27, TIOCMSET, [TIOCM_RTS|0x4000]) = 0
ioctl(27, TIOCMGET, [TIOCM_RTS|0x4000]) = 0
ioctl(27, TIOCMGET, [TIOCM_RTS|0x4000]) = 0
ioctl(27, TIOCMSET, [0x4000 /* TIOCM_??? */]) = 0
mprotect(0x7f2e6d9f3000, 4096, PROT_READ|PROT_WRITE) = 0