Philippe Mathieu-Daudé <f4...@amsat.org> writes:
> On 10/22/20 7:20 AM, Thomas Huth wrote: >> On 21/10/2020 18.31, Alex Bennée wrote: >>> Currently the test randomly fails if you are using a shared machine >>> due to contention on the well known port 1234. We can ameliorate this >>> a bit by picking a random non-ephemeral port although it doesn't >>> totally avoid the problem. While we could use a totally unique socket >>> address for debugging it's impossible to probe for gdb support of the >>> feature which makes this a sub-optimal but less fiddly option. >>> >>> Signed-off-by: Alex Bennée <alex.ben...@linaro.org> >>> --- >>> tests/acceptance/reverse_debugging.py | 6 ++++-- >>> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> Certainly better than before! > > I'd prefer another chardev that tcp, but as you said this is > already an improvement, so: We've supported sockets gdb and softmmu emulation for some time: -gdb unix:path=gdb.sock,server the trouble is detecting if the host installed gdb is going to connect before we try and fail after launching the VM. I think we might get away with a version probe: > luispm: I want to know ahead of time for my scripts if gdb can do a "target remote gdb.sock" <luispm> ajb-linaro, I don't think so. My guess is that GDB will always attempt to stablish a connection if the socket is valid. <luispm> ajb-linaro, Can you check the validity of the file before invoking GDB? <luispm> ajb-linaro, No concept of "is this particular remote target available?". > luispm: it's not that - I know the socket will exist but the older gdb just bombs out trying to read it. <luispm> ajb-linaro, Not good. <luispm> ajb-linaro, So is this a matter of an older GDB that doesn't support using socket files and a newer one that does? > luispm: I thought I might probe "help target remote" text but it's unchanged between versions > luispm: yes <luispm> ajb-linaro, I think the code is probably hidden within the "target remote" implementation. > luispm: and most distro gdb's don't at the moment > luispm: if I could work out the version it was added that might help <luispm> ajb-linaro, I see some bits of it were reverted at some point. <luispm> ajb-linaro, Let me check. <luispm> ajb-linaro, It looks like GDB 8.3 was the first stable to get it. > luispm: thanks - I'll see if I can script that up <luispm> ajb-linaro, Looks like they initially went with an explicit prefix of "unix:" before the socket. But then dropped that in favor of autodetecting the socket file. <luispm> ajb-linaro, The only thing I get for a GDB that doesn't support socket connections if "/run/user/1000/at-spi2-QTZBS0/socket: No such device or address." <luispm> *is* <luispm> This is 8.1 in Ubuntu 18.04. <luispm> master GDB says "Remote communication error. Target disconnected.: Connection reset by peer." > > Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org> > >> >> Reviewed-by: Thomas Huth <th...@redhat.com> >> -- Alex Bennée