'Re: No console, not even serial, does not work (init fails) - init from HEAD works'

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List:       freebsd-current
Subject:    Re: No console, not even serial, does not work (init fails) - init from HEAD works
From:       Nick Hibma <nick () van-laarhoven ! org>
Date:       2013-02-26 22:41:56
Message-ID: 2820BD0B-BCFA-4068-AFE7-D123630828E4 () van-laarhoven ! org
[Download RAW message or body]

[feels like I am talking to myself in this thread ...]

After copying the /usr/src/sbin/init/ directory from HEAD to 8.3-RELEASE and building \
init there (without changes), things started working again, and the image now \
succesfully boots. Thanks for that.

The downside of this approach is the lack of logging of the output of the console \
output. I've tried quickly to throw together a 'null' console which would make the \
console output at least appear in the output of 'dmesg -a', but that change requires \
a tty device, which I couldn' be asked to throw together. Ed was going to think this \
over, especially because a null console might come in handy in jails.

Hope this is of use to anyone.

Nick Hibma
nick@van-laarhoven.org

How many todos are on YOUR To Do lists? - GTD

On 19 Feb 2013, at 10:03, Nick Hibma wrote:

> Ed sent me a answer to my ramblings:
> 
> "It is indeed true that init(8) is a bit picky when you don't have a
> console. If /dev/console cannot be opened, init(8) will just break
> completely. This has been fixed in FreeBSD -HEAD, where I've extended
> init(8) to handle this gracefully, specifically for cases where you
> have hardware without a console or potentially want to run init(8) in
> a jail (though we're not there yet)."
> 
> http://svnweb.freebsd.org/base?view=revision&revision=232977
> 
> I'll try that, and will follow up here.
> 
> Nick Hibma
> nick@van-laarhoven.org
> 
> Collect, process, organize, review and do. - GTD
> 
> On 18 Feb 2013, at 20:30, Nick Hibma <nick@van-laarhoven.org> wrote:
> 
> > We run our NanoBSD images on Soekris and ALIX hardware. In some cases we need all \
> > available serial ports for other hardware like GPS, and modems. The boards have \
> > no video, so with all serial ports unavailable as a console no other console is \
> > available. 
> > The problem is that FreeBSD does not handle well the case where there is no \
> > console at all: 
> > 1) http://www.freebsd.org/cgi/query-pr.cgi?pr=bin/102515
> > 
> > fsck_ufs crashes (6.1-STABLE). Because of the unitialised console libc somehow \
> > gets corrupted and crashes fsck_ufs. This problem can be circumvented by \
> > replacing 'fsck -p' with 'fsck < /dev/null > /dev/null'. 
> > 2) In 8.3-RELEASE init exits prematurely because it cannot open /dev/console for \
> > reading and writing in setctty(). Removing the calls to _exit(1) in that function \
> > makes the boot complete. I haven't checked whether the fsck_ufs problem still \
> > appears as our builds run with a patched rc.d script. 
> > 
> > As far as I can see this is still a problem in CURRENT.
> > 
> > 
> > My attempt at resolving this was to create a null terminal in dev/null/null.c, \
> > see the patch below, but that did not work as expected. After booting the system \
> > with a modified init the response to 'echo > /dev/console' was 'Device not \
> > configured'. I've added another CN_* priority to make sure a null console does \
> > not take precedence over for example gdb console. 
> > 
> > Any pointers as to who/how to resolve this issue? Any reason why the null console \
> > approach does not work? 
> > Nick Hibma
> > nick@van-laarhoven.org
> > 
> > GTD: Time management for chaotic people.
> > 
> > Index: /usr/src/sys/sys/cons.h
> > ===================================================================
> > --- /usr/src/sys/sys/cons.h	(revision 242660)
> > +++ /usr/src/sys/sys/cons.h	(working copy)
> > @@ -69,10 +69,11 @@
> > 
> > /* values for cn_pri - reflect our policy for console selection */
> > #define	CN_DEAD		0	/* device doesn't exist */
> > -#define CN_LOW		1	/* device is a last restort only */
> > -#define CN_NORMAL	2	/* device exists but is nothing special */
> > -#define CN_INTERNAL	3	/* "internal" bit-mapped display */
> > -#define CN_REMOTE	4	/* serial interface with remote bit set */
> > +#define CN_NULL		1	/* no console at all */
> > +#define CN_LOW		2	/* device is a last restort only */
> > +#define CN_NORMAL	3	/* device exists but is nothing special */
> > +#define CN_INTERNAL	4	/* "internal" bit-mapped display */
> > +#define CN_REMOTE	5	/* serial interface with remote bit set */
> > 
> > /* Values for cn_flags. */
> > #define	CN_FLAG_NODEBUG	0x00000001	/* Not supported with debugger. */
> > Index: /usr/src/sys/dev/null/null.c
> > ===================================================================
> > --- /usr/src/sys/dev/null/null.c	(revision 242660)
> > +++ /usr/src/sys/dev/null/null.c	(working copy)
> > @@ -41,6 +41,9 @@
> > #include <sys/bus.h>
> > #include <sys/filio.h>
> > 
> > +#include <sys/cons.h>
> > +#include <sys/consio.h>
> > +
> > #include <machine/bus.h>
> > 
> > /* For use with destroy_dev(9). */
> > @@ -173,3 +176,45 @@
> > 
> > DEV_MODULE(null, null_modevent, NULL);
> > MODULE_VERSION(null, 1);
> > +
> > +static cn_probe_t null_cnprobe;
> > +static cn_init_t null_cninit;
> > +static cn_term_t null_cnterm;
> > +static cn_getc_t null_cngetc;
> > +static cn_putc_t null_cnputc;
> > +
> > +CONSOLE_DRIVER(null);
> > +
> > +static void
> > +null_cnprobe(struct consdev *cp)
> > +{
> > +        sprintf(cp->cn_name, "null");
> > +        cp->cn_pri = CN_NULL;
> > +}
> > +
> > +static void
> > +null_cninit(struct consdev *cp)
> > +{
> > +}
> > +
> > +
> > +static void
> > +null_cnputc(struct consdev *cp, int c)
> > +{
> > +	(void) cp;
> > +
> > +	(void) c;
> > +}
> > +
> > +static int
> > +null_cngetc(struct consdev * cp)
> > +{
> > +	(void) cp;
> > +	
> > +	return -1;
> > +}
> > +
> > +static void
> > +null_cnterm(struct consdev * cp)
> > +{
> > +}
> > 
> 
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