Re: Support for netconsole as default tty/console?
At Tue, 1 Apr 2014 10:34:27 +0200, Struan Bartlett wrote: > > On 31 March 2014 14:34, Andreas Schwab wrote: > > One Thousand Gnomes writes: > > > >> It's however implemented and present. The rest is between you and the > >> relevant Kconfig maintainer. I'm sure you count as an expert ;-) > > > > Indeed. > > > > http://lists.opensuse.org/opensuse-kernel/2014-03/msg00071.html > > I have just completed an implementation of a tty driver for > netconsole, which I was about to submit as a patch. When the kernel > command line is set accordingly (console=netcon0), it has the desired > effect of taking over output to /dev/console when it is loaded. Would > you say this work is wasted, or that it's worth submitting the patch > anyway? > > There are differences to the ttyprintk approach. ttyprintk is > currently kernel-only, and not available as a module. Actually, this can be easily fixed. I'm going to submit a patch (and another fix patch for the driver's error path). Note that they don't mean to object against your patching netconsole. I find also it more convenient to use directly netconsole. thanks, Takashi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
On 31 March 2014 14:34, Andreas Schwab wrote: > One Thousand Gnomes writes: > >> It's however implemented and present. The rest is between you and the >> relevant Kconfig maintainer. I'm sure you count as an expert ;-) > > Indeed. > > http://lists.opensuse.org/opensuse-kernel/2014-03/msg00071.html I have just completed an implementation of a tty driver for netconsole, which I was about to submit as a patch. When the kernel command line is set accordingly (console=netcon0), it has the desired effect of taking over output to /dev/console when it is loaded. Would you say this work is wasted, or that it's worth submitting the patch anyway? There are differences to the ttyprintk approach. ttyprintk is currently kernel-only, and not available as a module. ttyprintk adds special formatting to the output, which netconsole does not. (If netconsole were to provide special formatting, it might make sense for it to be syslog-compatible). In defence of netconsole providing a tty driver, many other output device modules already provide their own tty (i.e. do not rely on ttyprintk). Also, unlike ttyprintk, netconsole is already widely used and well documented on the web. Adding a tty driver to netconsole would be a natural extension of functionality for those already using it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
On Monday 31 of March 2014, One Thousand Gnomes wrote: > On Sat, 29 Mar 2014 15:54:24 +0100 > > Andreas Schwab wrote: > > Struan Bartlett writes: > > > Adding console=netconsole to the command line does not appear to have > > > the desired effect. I am not sure if this is because netconsole, > > > unlike the serial console, does not provide a tty. Can anyone advise > > > if this understanding is correct? If so, is there an independent > > > solution to this problem? > > > > It should not be hard to add a tty driver to netconsole, there are many > > examples to borrow from. > > Samo Pogacnik added a generic solution a few years ago. The ttyprintk > driver provides you with a tty/console whose 'hardware' is printk and > thus whatever system log device you are using. Is there a way to get two devices working as console? For example I would like to have console on tty0 and on netconsole at the same time. Right now only one, last console gets all userspace messages. > Alan -- Arkadiusz Miśkiewicz, arekm / maven.pl -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
One Thousand Gnomes writes: > It's however implemented and present. The rest is between you and the > relevant Kconfig maintainer. I'm sure you count as an expert ;-) Indeed. http://lists.opensuse.org/opensuse-kernel/2014-03/msg00071.html Andreas. -- Andreas Schwab, SUSE Labs, sch...@suse.de GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
On Mon, 31 Mar 2014 12:26:35 +0200 Andreas Schwab wrote: > One Thousand Gnomes writes: > > > Samo Pogacnik added a generic solution a few years ago. The ttyprintk > > driver provides you with a tty/console whose 'hardware' is printk and > > thus whatever system log device you are using. > > Unfortunately it's an EXPERT setting, thus typically not avaiable. It's however implemented and present. The rest is between you and the relevant Kconfig maintainer. I'm sure you count as an expert ;-) (and perhaps moving it into drivers/tty would also be sensible). Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
One Thousand Gnomes writes: > Samo Pogacnik added a generic solution a few years ago. The ttyprintk > driver provides you with a tty/console whose 'hardware' is printk and > thus whatever system log device you are using. Unfortunately it's an EXPERT setting, thus typically not avaiable. Andreas. -- Andreas Schwab, sch...@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
On Sat, 29 Mar 2014 15:54:24 +0100 Andreas Schwab wrote: > Struan Bartlett writes: > > > Adding console=netconsole to the command line does not appear to have > > the desired effect. I am not sure if this is because netconsole, > > unlike the serial console, does not provide a tty. Can anyone advise > > if this understanding is correct? If so, is there an independent > > solution to this problem? > > It should not be hard to add a tty driver to netconsole, there are many > examples to borrow from. Samo Pogacnik added a generic solution a few years ago. The ttyprintk driver provides you with a tty/console whose 'hardware' is printk and thus whatever system log device you are using. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
Struan Bartlett writes: > Thank you. I've begun investigating the sources in drivers/tty. Am I > correct in thinking that this only needs a tty driver, and not also a > serial driver? See arch/m68k/emu/nfcon.c for a somewhat minimal example (only output). Andreas. -- Andreas Schwab, sch...@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
On 29 March 2014 15:54, Andreas Schwab wrote: > Struan Bartlett writes: > >> Adding console=netconsole to the command line does not appear to have >> the desired effect. I am not sure if this is because netconsole, >> unlike the serial console, does not provide a tty. Can anyone advise >> if this understanding is correct? If so, is there an independent >> solution to this problem? > > It should not be hard to add a tty driver to netconsole, there are many > examples to borrow from. Thank you. I've begun investigating the sources in drivers/tty. Am I correct in thinking that this only needs a tty driver, and not also a serial driver? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Support for netconsole as default tty/console?
Struan Bartlett writes: > Adding console=netconsole to the command line does not appear to have > the desired effect. I am not sure if this is because netconsole, > unlike the serial console, does not provide a tty. Can anyone advise > if this understanding is correct? If so, is there an independent > solution to this problem? It should not be hard to add a tty driver to netconsole, there are many examples to borrow from. Andreas. -- Andreas Schwab, sch...@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Support for netconsole as default tty/console?
Hi I help maintain a range of raw metal hosts, VMs, and Amazon EC2 instances that boot Linux within secure private networks. Where possible, we connect raw metal hosts to a central logging server using serial lines, and use the console=ttyS0 kernel command line option to redirect not just kernel boot logs, but all boot script tty output, via the serial line for central logging. This is particularly useful, as when critical start-up scripts report issues to the console (as opposed to logs files) those issues can be monitored centrally, and diagnosed without the need to log in. In some cases, critical error messages are only logged to the console, and not to the logs files. Serial lines do not scale well and, on some of our VMs, and certainly on EC2 instances, platforms are headless and may be accessed only by our private network. As mentioned, our systems are running in known secure private networks accessible only to sysadmins, so authenticating access to the terminal output is not a particular concern. We have had a good experience of using netconsole to provide remote real-time access to the kernel logs during Linux boot, via our syslog server. However we have yet to find a reliable way to redirect all console output (i.e. start-up script not just kernel logs) via the private network to our logging server, as is possible via a serial line. We have tried to address the issue in user-space. Patching of boot scripts to pipe output via tee and socat has been attempted, but it is hard to make this work comprehensively, and it appears to interfere with standard shutdown scripts that expect all processes to be able to be killed (without terminating standard output/error pipes) before switching run levels. Adding console=netconsole to the command line does not appear to have the desired effect. I am not sure if this is because netconsole, unlike the serial console, does not provide a tty. Can anyone advise if this understanding is correct? If so, is there an independent solution to this problem? Failing that, is there general interest in a tty-capable (maybe output only) extension to the netconsole module? Kind regards -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
