Daniel P. Berrangé <berrange@redhat.com> writes:
On Thu, Feb 19, 2026 at 11:08:45AM +0100, Markus Armbruster wrote:
Daniel P. Berrangé <berrange@redhat.com> writes:
The error_report function can include the program name in any messages it prints. The qemu_log function has no equivalent behaviour.
This introduces support for a "program name" in the new messages API, which will be included by default for all binaries.
This change tweaks the output of the error_report function, adding a space between the program name and the location info.
Why?
Looking again, arguably that is fixing a pre-existing bug
The current code is:
if (!monitor_cur() && g_get_prgname()) { error_printf("%s:", g_get_prgname()); sep = " "; } switch (cur_loc->kind) { case LOC_CMDLINE: argp = cur_loc->ptr; for (i = 0; i < cur_loc->num; i++) { error_printf("%s%s", sep, argp[i]); sep = " "; } error_printf(": "); break; case LOC_FILE: error_printf("%s:", (const char *)cur_loc->ptr); if (cur_loc->num) { error_printf("%d:", cur_loc->num); } error_printf(" "); break; default: error_printf("%s", sep); }
Notice how we honour "sep" for LOC_CMDLINE but ignore it for LOC_FILE.
This works exactly as intended. To illustrate, add error_report("test, ignore"); to qdev_device_add(), then: $ cat t.cfg [device] driver = "usb-kbd" $ qemu-system-x86_64 -S -display none -machine usb=on -device usb-kbd -readconfig t.cfg -monitor stdio QEMU 10.2.50 monitor - type 'help' for more information qemu-system-x86_64: -device usb-kbd: test, ignore qemu-system-x86_64:t.cfg:2: test, ignore (qemu) device_add usb-kbd test, ignore The format program:sourcefile:lineno: message conforms to the GNU Coding Standards at <https://www.gnu.org/prep/standards/standards.html#Errors>, and matches common practice.
With the program name printing moved out into a separate function, the space is always printed. No change for LOC_CMDLINE, but new whitespace for LOC_FILE.
Should have changed this in a separate patch.
The qemu_log function will gain the program name. This can be easily seen with the 'log' trace backend, and how it is now more closely matching error_report output.
Before:
# qemu-system-x86_64 -object tls-creds-x509,id=t0,dir=fish -d 'trace:qcrypto*' qcrypto_tls_creds_x509_load TLS creds x509 load creds=0x5584e13937f0 dir=fish qcrypto_tls_creds_get_path TLS creds path creds=0x5584e13937f0 filename=ca-cert.pem path=<none> qemu-system-x86_64: Unable to access credentials fish/ca-cert.pem: No such file or directory
After:
# qemu-system-x86_64 -object tls-creds-x509,id=t0,dir=fish -d 'trace:qcrypto*' qemu-system-x86_64: qcrypto_tls_creds_x509_load TLS creds x509 load creds=0x5584e13937f0 dir=fish qemu-system-x86_64: qcrypto_tls_creds_get_path TLS creds path creds=0x5584e13937f0 filename=ca-cert.pem path=<none> qemu-system-x86_64: Unable to access credentials fish/ca-cert.pem: No such file or directory
When adding this the '-msg program-name=on|off' option is introduced, so that the program name (which is enabled by default) can be supressed if desired. This could be useful if '-msg guest-name=on' is being used as a more informative identifier.
Separate patch?
It is a bit of a borderline decision, but I felt the knob to turn it off should be in the same patch that force enables it.
Peter objected to making the logs more verbose by default, and I think he has a point. Perhaps having errors and logs share a general format is useful anyway, and perhaps making it even more configurable is as well. I figure we'd need separate configuration for logs and for error messages. Let's get to rough consensus before we debate the finer points like this one.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
With regards, Daniel