On Fri, Mar 16, 2018 at 07:45:18PM +0100, KONRAD Frederic wrote: > On 03/16/2018 05:34 PM, Peter Maydell wrote: > > On 16 March 2018 at 16:23, KONRAD Frederic <frederic.kon...@adacore.com> > > wrote: > > > Since the commit: > > > commit 4486e89c219c0d1b9bd8dfa0b1dd5b0d51ff2268 > > > Author: Stefan Hajnoczi <stefa...@redhat.com> > > > Date: Wed Mar 7 14:42:05 2018 +0000 > > > > > > vl: introduce vm_shutdown() > > > > > > GDB crash when qemu exits (at least on sparc-softmmu): > > > Remote communication error. Target disconnected.: Connection reset by > > > peer. > > > Quitting: putpkt: write failed: Broken pipe. > > > > > > So send a packet to kill GDB before we exit QEMU: > > > [Inferior 1 (Thread 0) exited normally] > > > > > > Signed-off-by: KONRAD Frederic <frederic.kon...@adacore.com> > > > --- > > > gdbstub.c | 7 +++++++ > > > include/exec/gdbstub.h | 2 ++ > > > vl.c | 2 ++ > > > 3 files changed, 11 insertions(+) > > > > We didn't send an exiting packet before commit 4486e89c219c0, > > so do you know why this worked before then? (Telling gdb we're > > exiting seems like the right thing, though.) > > > > Hmmm good question, I didn't had time to investigate in detail > > Before 4486e89c219c0: > > (gdb) tar rem :1234 > Remote debugging using :1234 > 0x40000000 in trap_table () > (gdb) c > Continuing. > Remote connection closed > > After 4486e89c219c0: > > (gdb) tar rem :1234 > Remote debugging using :1234 > 0x40000000 in trap_table () > (gdb) c > Continuing. > putpkt: write failed: Connection reset by peer. > > With the patch: > > (gdb) tar rem :1234 > Remote debugging using :1234 > 0x40000000 in trap_table () > (gdb) c > Continuing. > [Inferior 1 (Thread 0) exited normally] > > We use to have this patch in our repository to avoid the remote > connection closed above.
Previously pause_vcpus() didn't invoke the vm change state handler.
Therefore the gdbstub didn't tell GDB that the vcpu was being stopped
from gdb_vm_state_change().
Now vm_shutdown() invokes vm change state handlers so the gdbstub tells
GDB that the vcpu is stopping. As a result GDB sends a packet to query
the state of the vcpu - but QEMU terminates and closes the connection
partway through.
Here is the strace:
31365 poll([{fd=3, events=POLLIN}, {fd=7, events=POLLIN}, {fd=11,
events=POLLIN}, {fd=13, events=POLLIN}], 4, -1) = 1 ([{fd=13, revents=POLLIN}])
31365 recvfrom(13, "$T03thread:01;#05", 8192, 0, NULL, NULL) = 17
31365 poll([{fd=13, events=POLLIN}], 1, 0) = 1 ([{fd=13, revents=POLLIN}])
31365 sendto(13, "+", 1, 0, NULL, 0) = 1
31365 sendto(13, "$g#67", 5, 0, NULL, 0) = -1 EPIPE (Broken pipe)
31365 --- SIGPIPE {si_signo=SIGPIPE, si_code=SI_USER, si_pid=31365,
si_uid=1000} ---
The ugly error message is because QEMU doesn't respond to GDB's "$g#67"
message.
Your patch is making GDB exit gracefully.
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
signature.asc
Description: PGP signature
