Hi On Mon, Jan 11, 2016 at 10:13 AM, Paolo Bonzini <pbonz...@redhat.com> wrote: > > > On 11/01/2016 09:33, Michael Tokarev wrote: >> 11.12.2015 14:29, Ashley Jonathan wrote: >>> I have experienced a minor difficulty using QEMU with the "-serial pty" >>> option: >>> >>> If a process opens the slave pts device, writes data to it, then >>> immediately closes it, the data doesn't reliably get delivered to the >>> emulated serial port. This seems to be because a read of the master pty >>> device returns EIO on Linux if no process has the pts device open, even >>> when data is waiting "in the pipe". >>> >>> A fix seems to be for QEMU to keep the pts file descriptor open until the >>> pty is closed, as per the below patch. >> >> The patch looks fine, so >> >> Reviewed-by: Michael Tokarev <m...@tls.msk.ru> >> >> but I'd love to have an ACK from the maintainer about this one, >> or for it to pick it up. > > Ok, I'll pick it up after I've read up a bit more on PTYs.
That patch slows down qemu a lot when using -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0. I forgot a lot about how pty/pts work, and reading some man pages didn't help me much to understand the issue, I would suggest to revert it until a better solution is found. -- Marc-André Lureau
