Internally at AdaCore there is a test that randomly fails. The error message differs, though: Remote communication error. Target disconnected.: Arg list too long. Remote communication error. Target disconnected.: No error. Remote communication error. Target disconnected.: Not a directory. Looking into this, it seems to me that serial.c doesn't always preserve the correct errno, but remote.c seems to assume that it does. For example, ser-base.c:generic_readchar does a lot of work after do_readchar fails.
I think this isn't really solveable, as the ser-mingw code doesn't even use errno -- it makes Windows API calls.
I see now that the Windows serial_open implementation just sets errno, so perhaps that can be done elsewhere.
I have some patches to try to do this, but now I realize that I've only ever seen this error on Windows hosts. On Windows I had my patch just do 'errno = EIO' rather than try to translate Windows error codes, but I think that's not very good. Maybe the serial API has to change to throw exceptions instead.
https://sourceware.org/pipermail/gdb-patches/2023-September/202385.html
The master branch has been updated by Tom Tromey <tromey@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=4dda9cc4b03788d1cf0416b39a3ab3780caf27fd commit 4dda9cc4b03788d1cf0416b39a3ab3780caf27fd Author: Tom Tromey <tromey@adacore.com> Date: Fri Sep 1 11:04:58 2023 -0600 Fix latent bug in ser_windows_send_break The ClearCommBreak documentation says: If the function fails, the return value is zero. ser_windows_send_break inverts this check. This has never been noticed because the caller doesn't check the result. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30770
The master branch has been updated by Tom Tromey <tromey@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=602971b3863dcecf2daa5ffc0853a75a3131446c commit 602971b3863dcecf2daa5ffc0853a75a3131446c Author: Tom Tromey <tromey@adacore.com> Date: Fri Sep 1 11:01:33 2023 -0600 Introduce throw_winerror_with_name This introduces throw_winerror_with_name, a Windows analog of perror_with_name, and changes various places in gdb to call it. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30770
The master branch has been updated by Tom Tromey <tromey@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ad3cf8c64e6e4794fc48d28c90f20cbbfdc51ca4 commit ad3cf8c64e6e4794fc48d28c90f20cbbfdc51ca4 Author: Tom Tromey <tromey@adacore.com> Date: Tue Aug 29 07:20:22 2023 -0600 Change serial_setbaudrate to throw exception remote.c has this code: if (serial_setbaudrate (rs->remote_desc, baud_rate)) { /* The requested speed could not be set. Error out to top level after closing remote_desc. Take care to set remote_desc to NULL to avoid closing remote_desc more than once. */ serial_close (rs->remote_desc); rs->remote_desc = NULL; perror_with_name (name); The perror here cannot be correct, because if serial_setbaudrate did set errno, it may be obscured by serial_close. This patch changes serial_setbaudrate to throw an exception instead. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30770
The master branch has been updated by Tom Tromey <tromey@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=a2e0acea420cca881296c6fcf58920f3d7c05a45 commit a2e0acea420cca881296c6fcf58920f3d7c05a45 Author: Tom Tromey <tromey@adacore.com> Date: Fri Sep 1 12:11:37 2023 -0600 Change serial "open" functions to throw exception remote.c assumes that a failure to open the serial connection will set errno. This is somewhat true, because the Windows code tries to set errno appropriately -- but only somewhat, because it isn't clear that the "pex" code sets it, and the tcp code seems to do the wrong thing. It seems better to simply have the serial open functions throw on error. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30770
The master branch has been updated by Tom Tromey <tromey@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d69939bded50d76179f97284df35879a385cf8c0 commit d69939bded50d76179f97284df35879a385cf8c0 Author: Tom Tromey <tromey@adacore.com> Date: Wed Sep 6 08:33:46 2023 -0600 Change serial_send_break and serial_write to throw This changes serial_send_break and serial_write to throw exceptions rather than attempt to set errno and return an error indicator. This lets us correctly report failures on Windows. Both functions had to be converted in a single patch because one implementation of send_break works via write. This also introduces remote_serial_send_break to handle error checking when attempting to send a break. This was previously ignored. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30770
The master branch has been updated by Tom Tromey <tromey@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=0da23004a064e7149373b484fa671f2a2105ec9b commit 0da23004a064e7149373b484fa671f2a2105ec9b Author: Tom Tromey <tromey@adacore.com> Date: Tue Aug 29 08:22:09 2023 -0600 Change serial_readchar to throw This changes serial_readchar to throw an exception rather than trying to set and preserve errno. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30770
Fixed.
The master branch has been updated by Tom Tromey <tromey@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=74d8fa2df7e7844f9b1b8fac27fe7d0b82100ab0 commit 74d8fa2df7e7844f9b1b8fac27fe7d0b82100ab0 Author: СеÑгей ЧеÑнов <klen_s@mail.ru> Date: Fri Jan 19 11:01:18 2024 -0700 Fix remote serial read After closing "Bug 30770 - serial.c does not preserve errno correctly" https://sourceware.org/bugzilla/show_bug.cgi?id=30770 remote debugging became impossible due to an attempt to recv() by a call intended for the socket, and not for the character device file. The documentation implicitly states that it is possible to use the read() call to work with a socket. But this does not mean in the general case that it is permissible to use recv in the case of a non-socket. condition: os: Distributor ID: Ubuntu Description: Ubuntu 23.10 Release: 23.10 Codename: mantic libc: ldd (Ubuntu GLIBC 2.38-1ubuntu6) 2.38 kernel: Linux klen-dev-um790pro 6.5.0-14-generic #14-Ubuntu SMP PREEMPT_DYNAMIC Tue Nov 14 14:59:49 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux gdb: build from trank at 15.0.50.20231226-git GDB output: $ arm-kgp-eabi-gdb GNU gdb (Klen's_GNU_package_(KGP)_for_target::arm-kgp-eabi<rmprofile/lto>_host::x86_64-kgp-linux-gnu_znver4-avx512<<ílex>>) 15.0.50.20231226-git .... (gdb) tar ext /dev/ttyACM1 Remote debugging using /dev/ttyACM1 Remote communication error. Target disconnected: error while reading: Socket operation on non-socket. (gdb) after fix gdb work fine $ arm-kgp-eabi-gdb -q (gdb) tar ext /dev/ttyACM0 Remote debugging using /dev/ttyACM0 (gdb) mon swd Target voltage: 0.0V Available Targets: No. Att Driver STM32F40x M4 (gdb) att 1 Attaching to Remote target warning: No executable has been specified and target does not support determining executable automatically. Try using the "file" command. 0x08020c80 in ?? () (gdb) Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30770