Bug#868352: linux: Please enable USB_SERIAL_CONSOLE
On Wednesday, 28 July 2021 10:02:47 CEST Michael Stapelberg wrote: > Ben Hutchings writes: > > On Fri, 2017-07-14 at 20:34 +0200, Sascha Silbe wrote: > >> Source: linux > >> Version: 4.11.6-1 > >> > >> on some amd64 systems no native or PCI(e) serial ports are available > >> resp. possible. USB serial adapters are the only option to get a > >> serial console for debugging boot problems in this case. > > > > I think this case is too unusual to make it worth building in all the > > USB stuff needed to make this work on all x86 systems. > > I’d like to respectfully ask you to reconsider this position. > > Over the years, more and more mainboards have dropped all support for > any onboard serial ports. Using a USB serial console is nowadays often > the only option for getting boot messages to another computer. > > To make the USB console work, I had to build my own Debian kernel with > the following options changed: > > CONFIG_USB=y > CONFIG_USB_SERIAL=y > CONFIG_USB_SERIAL_CONSOLE=y > > Given Debian’s popularity for server scenarios, I think we should make > troubleshooting easier and have USB serial consoles just work. > > Could you please enable CONFIG_USB_SERIAL_CONSOLE=y? $ grep -E "(CONFIG_USB|CONFIG_USB_SERIAL|CONFIG_USB_SERIAL_CONSOLE)=" /boot/config-5.18.0-1-amd64 CONFIG_USB=m CONFIG_USB_SERIAL=m In drivers/usb/serial/Kconfig at config USB_SERIAL_CONSOLE, I see this: depends on USB_SERIAL=y Can you check whether the following kernel config works? CONFIG_USB=m CONFIG_USB_SERIAL=y CONFIG_USB_SERIAL_CONSOLE=y Preferably only make the changes on the amd64 config, thus not globally. F.e. on my RPi and Rock64 (arm), I don't need USB_SERIAL_CONSOLE to have a working serial console (connected to the GPIO pins). usbserial.ko is 135K on my 5.18.0-1-amd64 kernel, so that's another aspect that needs to be evaluated. Note that I'm only trying to find the smallest change possible. I don't know whether these changes have other 'side affects'. I also have no idea whether it will change anything wrt being considered. IOW: you may be wasting your time. But I do see most/all peripherals disappearing, except USB and the 'wontfix' decision was from almost 5 years ago. USB serial consoles tend to be rather cheap and it (therefor) may also result in better bug reports on the kernel. Cheers, Diederik signature.asc Description: This is a digitally signed message part.
Bug#868352: linux: Please enable USB_SERIAL_CONSOLE
Hi Ben, Ben Hutchings writes: > On Fri, 2017-07-14 at 20:34 +0200, Sascha Silbe wrote: >> Source: linux >> Version: 4.11.6-1 >> Severity: normal >> >> Dear Maintainer, >> >> on some amd64 systems no native or PCI(e) serial ports are available >> resp. possible. USB serial adapters are the only option to get a >> serial console for debugging boot problems in this case. Unfortunately >> the Debian amd64 kernels are built with USB_SERIAL_CONSOLE unset >> (because USB_SERIAL is not built-in) so even that option isn't >> available. When the BIOS text mode isn't working (e.g. high-res >> monitor with a BIOS that only supports up to FullHD) one is left >> without any working console device. > [...] > > I think this case is too unusual to make it worth building in all the > USB stuff needed to make this work on all x86 systems. I’d like to respectfully ask you to reconsider this position. Over the years, more and more mainboards have dropped all support for any onboard serial ports. Using a USB serial console is nowadays often the only option for getting boot messages to another computer. I ran into this issue yesterday using an AsRock B550 Taichi mainboard, which has no serial headers. To make the USB console work, I had to build my own Debian kernel with the following options changed: CONFIG_USB=y CONFIG_USB_SERIAL=y CONFIG_USB_SERIAL_CONSOLE=y This is very tedious, partly because a build takes 42 minutes even on my latest-gen Ryzen CPU, and also because I don’t want to maintain a custom kernel build indefinitely. I don’t think this is a niche use case, at least not among users of serial consoles: other users of Debian and Ubuntu are running into this issue, too, see for example: https://unix.stackexchange.com/q/425280/181634 https://askubuntu.com/q/1269623 Notably, both Fedora and Arch Linux (the 2 other distributions I can quickly check) ship their default kernel with CONFIG_USB_SERIAL_CONSOLE=y: --- /tmp/config-debian 2021-07-27 23:29:22.648166910 +0200 +++ /tmp/config-fedora 2021-07-27 23:29:12.734958768 +0200 @@ -1,4 +1,5 @@ -CONFIG_USB_SERIAL=m +CONFIG_USB_SERIAL=y +CONFIG_USB_SERIAL_CONSOLE=y CONFIG_USB_SERIAL_GENERIC=y CONFIG_USB_SERIAL_SIMPLE=m CONFIG_USB_SERIAL_AIRCABLE=m @@ -16,7 +17,7 @@ So Debian seems like the odd one out. Given Debian’s popularity for server scenarios, I think we should make troubleshooting easier and have USB serial consoles just work. Could you please enable CONFIG_USB_SERIAL_CONSOLE=y? Thank you! -- Best regards, Michael
Bug#868352: linux: Please enable USB_SERIAL_CONSOLE
Control: severity -1 wishlist Control: tag -1 wontfix On Fri, 2017-07-14 at 20:34 +0200, Sascha Silbe wrote: > Source: linux > Version: 4.11.6-1 > Severity: normal > > Dear Maintainer, > > on some amd64 systems no native or PCI(e) serial ports are available > resp. possible. USB serial adapters are the only option to get a > serial console for debugging boot problems in this case. Unfortunately > the Debian amd64 kernels are built with USB_SERIAL_CONSOLE unset > (because USB_SERIAL is not built-in) so even that option isn't > available. When the BIOS text mode isn't working (e.g. high-res > monitor with a BIOS that only supports up to FullHD) one is left > without any working console device. [...] I think this case is too unusual to make it worth building in all the USB stuff needed to make this work on all x86 systems. Ben. -- Ben Hutchings If the facts do not conform to your theory, they must be disposed of. signature.asc Description: This is a digitally signed message part
Bug#868352: linux: Please enable USB_SERIAL_CONSOLE
Source: linux Version: 4.11.6-1 Severity: normal Dear Maintainer, on some amd64 systems no native or PCI(e) serial ports are available resp. possible. USB serial adapters are the only option to get a serial console for debugging boot problems in this case. Unfortunately the Debian amd64 kernels are built with USB_SERIAL_CONSOLE unset (because USB_SERIAL is not built-in) so even that option isn't available. When the BIOS text mode isn't working (e.g. high-res monitor with a BIOS that only supports up to FullHD) one is left without any working console device. So please enable USB_SERIAL_CONSOLE (requires USB_SERIAL=y) for future kernels and consider setting one of the USB serial adapter drivers to built-in as well so that it's available before module loading. But even just USB_SERIAL_CONSOLE alone (with all USB serial drivers as modules) is likely better than the current situation; AFAICT the USB serial console should get activated as soon the the USB serial driver is loaded (haven't tested it, though). Sascha -- System Information: Debian Release: 8.8 APT prefers oldstable APT policy: (990, 'oldstable'), (500, 'oldstable-updates'), (100, 'stable'), (1, 'experimental') Architecture: amd64 (x86_64) Foreign Architectures: i386 Kernel: Linux 4.9.0-0.bpo.2-amd64 (SMP w/4 CPU cores) Locale: LANG=en_GB, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: systemd (via /run/systemd/system)
