help wanted with "/dev/cua1: Device or resource busy"

help wanted with "/dev/cua1: Device or resource busy"

Post by Norman Rams » Sun, 28 Nov 1993 11:07:03



I'm running the Yggdrasil LGX F93 kernel, and any attempt to use
/dev/cua1 (including to run setserial) results in "Device or resource
busy".  (Ditto /dev/ttyS1, unsurprisingly.)  I have a mouse on com1
(/dev/cua0), and I can use kermit to connect to the mouse and see
gibberish at 1200baud when I move it.  I have an external modem on
com2.

I checked the serial-FAQ, but didn't get far:
  -- there are no getty processes on the serial line, just on tty[1-4]
     (my four virtual consoles).  I checked both inittab and `ps aux`
  -- the FAQ suggests remaking the kernel, but I tried that and the
     kernel sources as distributed won't build.

I have an SMC Ethernet card plugged into the system that I have never
used.  Could it be causing the problem?  If so, is there a cure other
than ripping it out?  

Can anyone suggest any other cures?  My linux box is pretty useless if
I can't talk to the world...

Norman Ramsey

--
Norman Ramsey

 
 
 

help wanted with "/dev/cua1: Device or resource busy"

Post by Norman Rams » Tue, 30 Nov 1993 13:27:09


Quote:>I'm running the Yggdrasil LGX F93 kernel, and any attempt to use
>/dev/cua1 (including to run setserial) results in "Device or resource
>busy".  (Ditto /dev/ttyS1, unsurprisingly.)  

I re-jumpered the SMC Elite16 Combo Ethernet card to use IRQ 10 and
the problem went away.

Thanks all for the help I got here.

 
 
 

help wanted with "/dev/cua1: Device or resource busy"

Post by hil.. » Tue, 14 Dec 1993 20:04:01


I wasn't confident about whether fprintf() actually returned EOF if the
disk was full, so I intentionally filled my disk up and wrote a program
to use fprintf repeatedly and print its return value. It *did* start
returning EOF when df returned 0% free.  I then returned to the application
that originally gave me my doubts and found it working fine!  Using
cat and cp I created many large files, seemingly uncorrupt, long after
my disk had been supposedly filled.  I then erased everything and ran
e2fsck because I figure it must have started overwriting something.  E2fsck
found nothing wrong.  So where did it put the extra megabyte of data I
generated?  I have only one linux partition.

System:  Slackware 0.99.13, ext2 fs 0.3c, 16Mb RAM
/dev/hda2             214Mb   /
/dev/hda1             184Mb   /dos
  swap                 16Mb

 
 
 

help wanted with "/dev/cua1: Device or resource busy"

Post by Michael Fir » Wed, 15 Dec 1993 18:23:07



>returning EOF when df returned 0% free.  I then returned to the application

Did you run this test as a normal user, or as root?
Quote:>that originally gave me my doubts and found it working fine!  Using
>cat and cp I created many large files, seemingly uncorrupt, long after
Same question!!
>my disk had been supposedly filled.  I then erased everything and ran
>e2fsck because I figure it must have started overwriting something.  E2fsck
>found nothing wrong.  So where did it put the extra megabyte of data I
>generated?  I have only one linux partition.

The Linux system reserves some space on the disk for root use, the default
amount with the Ext2 file system is 5% of the disk capacity. It appears that
when the system reports 0% free with 'df' this extra 5% is still available.
Presumably the reason is to still let root use the system when someone has
filled the disk with rubbish!!
The same feature is in an old BSD 4.2 machine I used, and probably in most
Unixes, but most commercial unix machines have disks large enough not to get
full easily :-)

Quote:

>System:  Slackware 0.99.13, ext2 fs 0.3c, 16Mb RAM
>/dev/hda2             214Mb   /
>/dev/hda1             184Mb   /dos
>  swap                 16Mb

Michael

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help wanted with "/dev/cua1: Device or resource busy"

Post by Andreas Kle » Sat, 25 Dec 1993 18:10:12




>>returning EOF when df returned 0% free.  I then returned to the application
>Did you run this test as a normal user, or as root?
>>that originally gave me my doubts and found it working fine!  Using
>>cat and cp I created many large files, seemingly uncorrupt, long after
>Same question!!
>>my disk had been supposedly filled.  I then erased everything and ran
>>e2fsck because I figure it must have started overwriting something.  E2fsck
>>found nothing wrong.  So where did it put the extra megabyte of data I
>>generated?  I have only one linux partition.
>The Linux system reserves some space on the disk for root use, the default
>amount with the Ext2 file system is 5% of the disk capacity. It appears that
>when the system reports 0% free with 'df' this extra 5% is still available.
>Presumably the reason is to still let root use the system when someone has
>filled the disk with rubbish!!
>The same feature is in an old BSD 4.2 machine I used, and probably in most
>Unixes, but most commercial unix machines have disks large enough not to get
>full easily :-)

I'd like to say that this is a feature of the Berkeley Fast File System.
That fs type is called 4.2 on SunOS and ufs in Solaris 2.X and in the
Unix world on intel based SVR4 Unix machines.

The newfs/mkfs reserves default 10% of space for optimization purposes (to
prevent fragmentation of files). On larger disks one should reduce that to
perhaps 5% using the utility tunefs that comes along with the ufs filesystem
on that machines.

        Andreas ///
--
Andreas Klemm                 /\/\____ Wiechers & Partner Datentechnik GmbH

 
 
 

1. /dev/ttyS2 (/dev/cua2) reports "device or resource busy" on kernel 2.1.95

I have just upgraded my kernel from 2.1.77 to 2.1.95

I use isapnp tools to set the IRQ and I/O address of my modem, then
setserial
to tell the driver that /dev/ttyS2 is where it is.

This worked fine on 2.1.77 kernel but now I get the message that the
"device or resource busy", when I attempt to open it (with say, dip
or kermit). Nothing else is using the port.

What has changed between these two kernel releases that would cause
this?

(also tried /dev/cua2 (which is being 'deprecated') to the same
effect...
works on 2.1.77 and is busy on 2.1.95)

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