On 08/12, Oleg Nesterov wrote: > > > I will investigate tomorrow, but I am almost sure gdb is > > wrong. > > Yes, this seems to be true... Tomorrow.
Can't sleep because of this problem ;) So, the patch below fixes the problem, and gdb + /proc/ugdb seems to work. Indeed, gdb sees that this fd is not pipe/tcp and uses the "hardwire" serial_ops, but hardwire_readchar() doesn't play well with select(). Please teach gdb to use poll/select ? Oleg. --- gdb-7.1/gdb/ser-unix.c +++ gdb-7.1/gdb/ser-unix.c @@ -452,7 +452,7 @@ hardwire_raw (struct serial *scb) static int wait_for (struct serial *scb, int timeout) { -#ifdef HAVE_SGTTY +#if 1 while (1) { struct timeval tv; @@ -474,13 +474,14 @@ wait_for (struct serial *scb, int timeou else numfds = gdb_select (scb->fd + 1, &readfds, 0, 0, 0); - if (numfds <= 0) + if (numfds <= 0) { if (numfds == 0) return SERIAL_TIMEOUT; else if (errno == EINTR) continue; else return SERIAL_ERROR; /* Got an error from select or poll */ + } return 0; }