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Message-ID: <4A270CCD.2020708@gmail.com>
Date: Wed, 03 Jun 2009 17:52:45 -0600
From: Robert Hancock <hancockrwd@gmail.com>
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To: stefan verse <stefan.verse@post.rwth-aachen.de>
CC: linux-kernel@vger.kernel.org
Subject: Re: possible Bug in IOAPIC concerning serial 8250
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stefan verse wrote:
> Hello,
> i know, no good place to start, but my problem is a little bit
> unspecific concerning Problems with IOAPIC concerning serrial driver
> 8250 :
> 
> 1. serial driver 8250 is loaded, but /dev/ttyS0 is unusable
> 
> 2. hardware is a d945gclf2 mini-itx board from intel, distribution is
> easyvdr 0.6.06., Kernel Version is 2.6.29.3, serial port is activated in
> BIOS, BIOS rev LF94510J.86A.0171.2009.0403.0118
> 
> dmesg reports :
> [   21.682611] Serial: 8250/16550 driver, 1 ports, IRQ sharing disabled
> [   21.682789] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> [   21.711689] 00:09: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> 
> and lsmod :
> 8250_pci               27412  0
> 8250_pnp               14036  0
> 8250                   20516  2 8250_pci,8250_pnp
> serial_core            18708  1 8250
> 
> so driver is loaded 
> 
> ls -lpr /dev/ttyS0
> crw-rw-rw- 1 root tty 4, 64 2009-06-03 07:55 /dev/ttyS0
> seems ok to me
> 
> but cat < /dev/ttyS0 gives :
> cat: -: Eingabe-/Ausgabefehler                  (I/O Error)
> 
> /proc/interrupts is missing driver for irq4 :

I think this is normal, the driver only claims the interrupt while the 
device is actually open. Do any dmesg messages result from trying to cat 
the device?