patch-1.3.25 linux/Documentation/networking/z8530drv.txt

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diff -u --recursive --new-file v1.3.24/linux/Documentation/networking/z8530drv.txt linux/Documentation/networking/z8530drv.txt
@@ -0,0 +1,953 @@
+// 950824: note -- I will upload the new version 1.9 to ftp.ucsd.edu
+//         as soon as possible... 
+//
+// ******
+// ****** The driver has a  n e w  MAJOR number (34) now! ******
+// ******
+//
+// please remake /dev/sc*:
+//
+// mknod /dev/sc1 c 34 0
+// mknod /dev/sc2 c 34 1
+// mknod /dev/sc3 c 34 2
+// mknod /dev/sc4 c 34 3
+//
+// (and so on...)
+//
+// -dl1bke-
+
+This is a subset of the documentation. To use this driver you MUST have the
+full package from:
+
+Internet:
+=========
+
+ftp.ucsd.edu:/hamradio/packet/tcpip/incoming/z8530drv-1.9.dl1bke.tar.gz
+
+[
+  if you can't find it there, try:
+  .../tcpip/linux/z8530drv-1.9.dl1bke.tar.gz
+
+]
+
+and various mirrors (i.e. nic.switch.ch)
+
+AX.25 BBS
+=========
+
+UNIX @ DB0ACH.#NRW.DEU.EU, subject: Z8530D19.Pxx/Pyy
+
+(AX.25 call: DB0ACH-8)
+
+and various BBS that received the file through AUTO7P or 7PSERV
+with the filename Z8530D19.TGZ
+
+
+---------------------------------------------------------------------------
+
+
+	 SCC.C - Linux driver for Z8530 based HDLC cards for AX.25      
+
+   ********************************************************************
+
+        (c) 1994 by Joerg Reuter DL1BKE
+
+        portions (c) 1994 Hans Alblas PE1AYX
+        and      (c) 1993 Guido ten Dolle PE1NNZ
+
+        for the complete copyright notice see >> Copying.Z8530DRV <<
+
+   ******************************************************************** 
+
+
+0. Installation of the package
+==============================
+
+Run SCC-Install. If one (or more) of the patches fails PLEASE consult 
+chapter 2 (and READ IT of course!)
+
+
+
+1. Initialization and attachment of the channels
+================================================
+
+To use the driver, 3 steps must be performed:
+
+     1. Global initialization of the driver in the kernel
+     2. Setup of parameters with sccinit
+     2. Attachment of each channel in the packet software
+
+The global initialization is needed to reset all SCCs and to 
+install a common interrupt handler.  Also, the hardware addresses 
+of the chips are defined in this step.  In the second step, each 
+channel is set up for the intended use.
+
+
+
+1.1. Initialization
+===================
+
+Initialization of the hardware is performed by setting the defines and
+variables in the file "/linux/drivers/char/scc_config.h". You can change 
+a number of parameters.
+
+
+
+################################################################################################
+# For OptoSCC card e.g:
+#
+
+int     Nchips       = 2        ; /* number of chips */
+io_port Vector_Latch = 0x168    ; /* addr. of INTACK-Latch (0 for poll mode)
+*/
+int     Ivec         = 9        ; /* interrupt vector */
+long    Clock        = 4915200  ; /* frequency of the scc clock */
+char    Pclk         = 1        ; /* use PCLK (1) or RTxC (0) */
+char    Board        = PA0HZP   ; /* what type of SCC card do you use? */
+int     Option       = 0        ; /* command for extra hardware */
+io_port Special_Port = 0        ; /* port address for special hardware */
+                                  /* (for EAGLE, PC100, PRIMUS, DRSI) */
+
+                        /*      ^  never remove the semicolon !! */
+
+
+/*                      Channel    A      B         Chip        */
+/*                               ============     ========      */
+/* Control ports:                                               */
+
+io_port SCC_ctrl[MAXSCC * 2] =  {0x152, 0x150,  /* ...one...    */
+                                 0x156, 0x154,  /* ...two...    */
+                                     0,     0,  /* ...three...  */
+                                     0,     0}; /* ...four...   */
+			
+
+/* Data ports:							*/
+
+io_port SCC_data[MAXSCC * 2] =  {0x153, 0x151,	/* ...one...	*/
+				 0x157, 0x155,	/* ...two...	*/
+				     0,     0,	/* ...three...	*/
+				     0,     0};	/* ...four...	*/
+
+
+/* set to '1' if you have and want ESCC chip (8580/85180/85280) support */
+
+/*					      Chip	*/
+/*				            ========   	*/
+int SCC_Enhanced[MAXSCC] =	{0,	/* ...one...	*/
+				 0,  	/* ...two...	*/
+				 0,  	/* ...three...	*/
+				 0};	/* ...four...	*/
+
+/* some useful #defines. You might need them or not */
+
+#define VERBOSE_BOOTMSG 1
+#undef  SCC_DELAY		/* perhaps a 486DX2 is a *bit* too fast */
+#undef  SCC_LDELAY		/* slow it even a bit more down */
+#undef  DONT_CHECK		/* don't look if the SCCs you specified are available */
+
+
+/*********** END OF CONFIGURATION PARAMETERS ********************************************/
+
+
+
+
+################################################################################################
+# For Baycom (U)SCC card e.g:
+#
+
+int     Nchips	     = 2	; /* number of chips */
+io_port Vector_Latch = 0	; /* addr. of INTACK-Latch (0 for poll mode) */
+int     Ivec	     = 7	; /* interrupt vector */
+long    Clock	     = 4915200	; /* frequency of the scc clock */
+char	Board	     = BAYCOM	; /* what type of SCC card do you use? */
+int	Option	     = 0	; /* command for extra hardware */
+io_port Special_Port = 0	; /* port address for special hardware */
+				  /* (for EAGLE, PC100, PRIMUS, DRSI) */
+
+			/*      ^  never remove the semicolon !! */
+			
+
+
+/* 			Channel    A      B	    Chip	*/
+/*			         ============	  ========	*/
+/* Control ports:						*/
+
+io_port SCC_ctrl[MAXSCC * 2] = 	{0x304, 0x305,  /* ...one... 	*/
+				 0x306, 0x307,  /* ...two...	*/
+				     0,     0,  /* ...three...	*/
+				     0,     0}; /* ...four...	*/
+
+/* Data ports:							*/
+
+io_port SCC_data[MAXSCC * 2] =  {0x300, 0x301,	/* ...one...	*/
+				 0x302, 0x303,	/* ...two...	*/
+				     0,     0,	/* ...three...	*/
+				     0,     0};	/* ...four...	*/
+
+
+/* set to '1' if you have and want ESCC chip (8580/85180/85280) support */
+
+/*					      Chip	*/
+/*				            ========   	*/
+int SCC_Enhanced[MAXSCC] =	{0,	/* ...one...	*/
+				 0,  	/* ...two...	*/
+				 0,  	/* ...three...	*/
+				 0};	/* ...four...	*/
+
+/* some useful #defines. You might need them or not */
+
+#define VERBOSE_BOOTMSG 1
+#undef  SCC_DELAY		/* perhaps a 486DX2 is a *bit* too fast */
+#undef  SCC_LDELAY		/* slow it even a bit more down */
+#undef  DONT_CHECK		/* don't look if the SCCs you specified are available */
+
+After you changed a parameter you have to recompile a new kernel image file.
+
+The channel number ranges from 0 to (2 * Nchips) - 1,
+where Nchips is the number of chips.
+
+The crystal clock is specified as 4.9152 MHz.  Other frequencies 
+can be used, and this parameter should be adjusted accordingly.
+
+
+You can define your scc type with Board
+
+   SCC type                 value
+   ---------------------------------
+   PA0HZP SCC card          PA0HZP
+   EAGLE card               EAGLE
+   PC100 card               PC100
+   PRIMUS-PC (DG9BL) card   PRIMUS
+   BayCom (U)SCC card       BAYCOM
+
+
+NOTE:
+=====
+
+If you only know the parameters for the PE1CHL driver for DOS,
+run gencfg. It will generate the correct port addresses (I hope).
+Its parameters are exactly the same as the ones you use with
+the "attach scc" command in net, except that the string "init" must 
+not appear. Example:
+
+gencfg 2 0x150 4 2 0 1 0x168 9 4915200 
+
+will print a short form of scc_config.h for the OptoSCC to stdout. 
+("short" <=> few comments).
+
+gencfg 2 0x300 2 4 5 -4 0 7 4915200 0x10
+
+does the same for the BayCom USCC card. I my opinion it is much easier
+to edit scc_config.h... 
+
+
+1.2 initializing the driver on bootup
+=====================================
+
+
+To setup a number parameters you must run /sbin/sccinit from one
+of your rc.*-files. This has to be done BEFORE the start of
+NET or the ax25attach. Sccinit reads the file /etc/z8530drv.rc
+and sets the MODEM and KISS parameters. A sample file is
+delivered with this package. Change it to your needs:
+
+Each channel definition is divided into three sections. An
+example for /dev/sc1:
+
+# DEVICE
+
+device /dev/sc1		# the device for the following params
+
+# MODEM
+
+speed 1200		# the default baudrate
+clock dpll		# clock source: 
+			# 	dpll     = normal halfduplex operation
+			# 	external = MODEM provides own Rx/Tx clock
+			#	divider  = use fullduplex divider if
+			#		   installed (1)
+mode nrzi		# HDLC encoding mode
+			#	nrzi = 1k2 MODEM, G3RUH 9k6 MODEM
+			#	nrz  = DF9IC 9k6 MODEM
+# KISS (Layer 1)
+
+txdelay 36              # (see chapter 1.4)
+persist 64
+slot    8
+tail    8
+fulldup 0
+wait    12
+min     3
+maxkey  7
+idle    3
+maxdef  120
+group   0
+txoff   off
+softdcd on                   
+slip    off
+
+The order WITHIN these sections is unimportant. The order OF these
+sections IS important. The MODEM parameters are set with the first
+recognized KISS paramer...
+
+Please note that you can initialize the board only once after boot. 
+You can change all paramters but "mode" and "clock" later with the
+Sccparam program or through KISS. Just to avoid securety holes... 
+
+(1) this divider is usually mounted on the SCC-PBC (PA0HZP) or not
+    present at all (BayCom). It feeds back the output of the DPLL 
+    (digital pll) as transmit clock. Using this mode without a divider 
+    installed will normally result in keying the transceiver until 
+    maxkey expires --- of course without sending anything (useful).
+
+
+1.3. Attach commands
+====================
+
+When the linux has startup, the SCC driver has been initialized,
+you can attach the channels in your packet software. This is done
+by open the scc devices by using the attach asy command.
+The SCC-drivers emulates the scc devices as serial asy ports,
+this means e.g. that the baudrate can be set in the attach command.
+
+
+Example Wampes:
+
+#############################################################################################
+# Wampes device attach
+# NOTE: Interfacename and the device must be the same!!
+# Usage: attach asy 0 0 slip|vjslip|ax25ui|ax25i|nrs|kissui <label> 0 <mtu> <speed> [ip_addr]
+#
+attach asy 0 0 kissi sc1 256 256 1200    # Attach SCC channel 1 in 1200 baud
+attach asy 0 0 kissi sc2 256 256 1200    # Attach SCC channel 2 in 1200 baud
+attach asy 0 0 kissui sc3 256 256 38400  # Attach SCC channel 3 in 38400 baud
+attach asy 0 0 kissui sc4 256 256 9600   # Attach SCC channel 4 in 9600 baud
+#                ^
+#                 for WAMPES 921229 use here: ax25
+#
+
+Example JNOS:
+
+############################################
+# JNOS device attach
+#
+#attach asy sc1 0 ax25 sc1 256 256 1200
+#attach asy sc2 0 ax25 sc2 256 256 1200
+#attach asy sc3 0 ax25 sc3 256 256 300
+#attach asy sc4 0 ax25 sc4 256 256 4800
+#
+#
+
+
+It allows AX.25 communication without a TNC.  Only a MODEM is
+needed. The parameters have the same meaning as in KISS mode.
+In fact, the AX.25 mode is emulating an extended KISS TNC, so
+the same commands can be used to set the parameters of the
+interface (see below).
+
+To be able to run fullduplex using an SCC in AX.25 mode, an 
+external divider must be available, that divides the baudrate 
+generator clock available on the TRxC pin by 32, and puts the 
+resulting signal on the RTxC pint of the same channel of the SCC.  
+Such a divider is not necessary for normal CSMA packet radio 
+operation, but interrupt overhead is slightly reduced if you 
+still install it.  
+
+
+
+1.4. Displaying SCC Parameters:
+===============================
+
+Once a SCC channel has been attached, the parameter settings and 
+some statistic information can be shown using the param program:
+
+dl1bke-u:~$ sccstat /dev/sc1
+
+Parameters:
+
+speed       : 1200 baud
+txdelay     : 36
+persist     : 255
+slottime    : 0
+txtail      : 8
+fulldup     : 1
+waittime    : 12
+mintime     : 3 sec
+maxkeyup    : 7 sec
+idletime    : 3 sec
+maxdefer    : 120 sec
+group       : 0x00
+txoff       : off
+softdcd     : on
+SLIP        : off
+
+Status:
+
+HDLC                  Z8530           Interrupts         Queues
+-----------------------------------------------------------------------
+Sent       :     273  RxOver :     0  RxInts :   125074  RxQueue :    0
+Received   :    1095  TxUnder:     0  TxInts :     4684  TxQueue :    0
+RxErrors   :    1591                  ExInts :    11776
+KissErrors :       0                  SpInts :     1503  NoSpace :    0
+Tx State   :    idle
+
+Memory allocated:
+
+Total  :    1
+RxAlloc:    0
+TxAlloc:    1
+
+
+The status info shown is:
+
+Sent		- number of frames transmitted
+Received	- number of frames received
+RxErrors	- number of receive errors (CRC, ABORT)
+KissErrors	- number of KISS errors (should be zero...)
+Tx State	- status of the Tx interrupt handler: idle/busy/active/tail (2)
+RxOver		- number of receiver overruns
+TxUnder		- number of transmitter underruns     
+RxInts		- number of receiver interrupts
+TxInts		- number of transmitter interrupts
+EpInts		- number of receiver special condition interrupts
+SpInts		- number of external/status interrupts
+RxQueue		- number of received packets enqueued for this channel
+TxQueue		- number of packets enqueued for Tx
+NoSpace		- number of times the receiver buffer pool was found empty
+
+
+An overrun is abnormal. If lots of these occur, the product of
+baudrate and number of interfaces is too high for the processing
+power of you computer. If "Space" errors occur, specify a higher
+number of buffers in the "scc.h" file.
+
+
+1.5 Setting Parameters
+======================
+
+
+The setting of parameters of the emulated KISS TNC is done in the 
+same way in the SCC driver. You can change parameters by using
+the command param in NET or NOS
+
+     param <iface> <paramname> <value>
+
+or use the program "sccparam":
+
+     sccparam <device> <paramname> <decimal-|hexadecimal value>
+
+You can change the following parameters:
+
+param	    : value
+------------------------
+speed       : 1200
+txdelay     : 36
+persist     : 255
+slottime    : 0
+txtail      : 8
+fulldup     : 1
+waittime    : 12
+mintime     : 3
+maxkeyup    : 7
+idletime    : 3
+maxdefer    : 120
+group       : 0x00
+txoff       : off
+softdcd     : on
+SLIP        : off
+
+
+The parameters have the following meaning:
+
+speed:
+     The baudrate on this channel in bits/sec
+
+     Example: sccparam /dev/sc4 speed 9600
+
+txdelay:
+     The delay (in units of 10ms) after keying of the 
+     transmitter, until the first byte is sent. This is usually 
+     called "TXDELAY" in a TNC.  When 0 is specified, the driver 
+     will just wait until the CTS signal is asserted. This 
+     assumes the presence of a timer or other circuitry in the 
+     MODEM and/or transmitter, that asserts CTS when the 
+     transmitter is ready for data.
+     A normal value of this parameter is 30-36.
+
+     Example: sccparam /dev/sc1 txd 20
+
+persist:
+     This is the probability that the transmitter will be keyed 
+     when the channel is found to be free.  It is a value from 0 
+     to 255, and the probability is (value+1)/256.  The value 
+     should be somewhere near 50-60, and should be lowered when 
+     the channel is used more heavily.
+
+     Example: sccparam /dev/sc3 persist 20
+
+slottime:
+     This is the time between samples of the channel. It is 
+     expressed in units of 10ms.  About 200-300 ms (value 20-30) 
+     seems to be a good value.
+
+     Example: sccparam /dev/sc1 slot 20
+
+tail:
+     The time the transmitter will remain keyed after the last 
+     byte of a packet has been transferred to the SCC. This is 
+     necessary because the CRC and a flag still have to leave the 
+     SCC before the transmitter is keyed down. The value depends 
+     on the baudrate selected.  A few character times should be 
+     sufficient, e.g. 40ms at 1200 baud. (value 4)
+     The value of this parameter is in 10ms units.
+
+     Example: sccparam /dev/sc3 4
+
+full:
+     The full-duplex mode switch. This can be one of the folowing 
+     values:
+
+     0:   The interface will operate in CSMA mode (the normal 
+          half-duplex packet radio operation)
+     1:   Fullduplex mode, i.e. the transmitter will be keyed at 
+          any time, without checking the received carrier.  It 
+          will be unkeyed when there are no packets to be sent.
+     2:   Like 1, but the transmitter will remain keyed, also 
+          when there are no packets to be sent.  Flags will be 
+          sent in that case, until a timeout (parameter 10) 
+          occurs.
+
+     Example: sccparam /dev/sc1 fulldup off
+
+wait:
+     The initial waittime before any transmit attempt, after the 
+     frame has been queue for transmit.  This is the length of 
+     the first slot in CSMA mode.  In fullduplex modes it is
+     set to 0 for maximum performance.
+     The value of this parameter is in 10ms units. 
+
+     Example: sccparam /dev/sc2 wait 4
+
+maxkey:
+     The maximal time the transmitter will be keyed to send 
+     packets, in seconds.  This can be useful on busy CSMA 
+     channels, to avoid "getting a bad reputation" when you are 
+     generating a lot of traffic.  After the specified time has 
+     elapsed, no new frame will be started. Instead, the trans-
+     mitter will be switched off for a specified time (parameter 
+     min), and then the selected algorithm for keyup will be 
+     started again.
+     The value 0 as well as "off" will disable this feature, 
+     and allow infinite transmission time. 
+
+     Example: sccparam /dev/sc1 maxk 20
+
+min:
+     This is the time the transmitter will be switched off when 
+     the maximum transmission time is exceeded.
+
+     Example: sccparam /dev/sc4 min 10
+
+idle
+     This parameter specifies the maximum idle time in fullduplex 
+     2 mode, in seconds.  When no frames have been sent for this 
+     time, the transmitter will be keyed down.  A value of 0 is
+     has same result as the fullduplex mode 1. This parameter
+     can be disabled.
+
+     Example: sccparam /dev/sc3 idle off	# transmit forever
+
+maxdefer
+     This is the maximum time (in seconds) to wait for a free channel
+     to send. When this timer expires the transmitter will be keyed 
+     IMMEDIATLY. If you love to get trouble with other users you
+     should set this to a very low value ;-)
+
+     Example: sccparam /dev/sc1 maxdefer 240	# 2 minutes
+
+
+txoff:
+     When this parameter has the value 0, the transmission of packets
+     is enable. Otherwise it is disabled.
+
+     Example: sccparam /dev/sc3 txoff on
+
+group:
+     It is possible to build special radio equipment to use more than 
+     one frequency on the same bad, e.g. using several receivers and 
+     only one transmitter that can be switched between frequencies.
+     Also, you can connect several radios that are active on the same 
+     band.  In these cases, it is not possible, or not a good idea, to 
+     transmit on more than one frequency.  The SCC driver provides a 
+     method to lock transmitters on different interfaces, using the 
+     "param <interface> group <x>" command.  This will only work when 
+     you are using CSMA mode (parameter full = 0).
+     The number <x> must be 0 if you want no group restrictions, and 
+     can be computed as follows to create restricted groups:
+     <x> is the sum of some OCTAL numbers:
+
+     200  This transmitter will only be keyed when all other 
+          transmitters in the group are off.
+     100  This transmitter will only be keyed when the carrier 
+          detect of all other interfaces in the group is off.
+     0xx  A byte that can be used to define different groups.  
+          Interfaces are in the same group, when the logical AND 
+          between their xx values is nonzero.
+
+     Examples:
+     When 2 interfaces use group 201, their transmitters will never be 
+     keyed at the same time.
+     When 2 interfaces use group 101, the transmitters will only key 
+     when both channels are clear at the same time.  When group 301, 
+     the transmitters will not be keyed at the same time.
+
+     Don't forget to convert the octal numbers into decimal before
+     you set the parameter.
+
+     Example: (to be written)
+
+softdcd:
+     use a software dcd instead of the real one... Useful for a very
+     slow squelch.
+
+     Example: sccparam /dev/sc1 soft on
+
+
+slip:
+     use slip encoding instead of kiss
+
+     Example: sccparam /dev/sc2 slip on
+
+
+
+2. Problems
+===========
+
+We are poking around in somebody else's code, so everything may change
+from one patchlevel to another... If the patches fail, try the
+following:
+
+2.1 /linux/drivers/char/Makefile
+================================
+
+Add "scc.o" to the definition of OBJS and "scc.c" to SRCS
+
+
+2.2 /linux/include/linux/tty_driver.h
+=====================================
+
+add the following DEFINE:
+
+#define TTY_DRIVER_TYPE_SCC 0x0005
+
+
+2.3 /linux/drivers/char/tty_io.c
+================================
+
+in tty_init() add the line
+
+	kmem_start=scc_init(kmem_start);
+
+just before "return kmem_start".
+
+2.4 /linux/arch/i386/config.in
+==============================
+
+somewhere in that file add:
+
+	comment 'Z8530 SCC driver for Amateur Packet Radio'
+	bool 'KISS emulator for Z8530 based HDLC cards' CONFIG_SCC y
+	comment ''
+  
+
+
+2.5 Other problems
+==================
+
+If you have tx-problems with your BayCom USCC card please check
+the manufacturer of the 8530. SGS chips have a slightly
+different timing. Try Zilog... I have no information if this
+driver works with baudrates higher than 1200 baud. A solution is
+to write to register 8 instead to the data port, but this won't
+work with the ESCC chips *SIGH!*
+
+I got reports that the driver has problems on some 386-based systems.
+(i.e. Amstrad) Those systems have a bogus AT bus timing which will
+lead to delayed answers on interrupts. You can recognize these
+problems by looking at the output of Sccstat for the suspected
+port. See if it shows under- and overruns you own such a system.
+Perhaps it will help if you simplify the scc_isr() function a bit.
+You'll find a slightly faster version in the files scc_isr_intack
+or scc_isr_novec.
+
+
+Delayed processing of received data: This depends on
+
+- the kernel version
+
+- kernel profiling compiled or not
+
+- the rather slow receiver in tty_io.c
+
+- a high interrupt load
+
+- a high load of the maching --- running X, Xmorph, XV and Povray,
+  while compiling the kernel... hmm ... even with 32 MB RAM ...  ;-)
+
+- NET's speed itself.
+
+
+Kernel panics (based on excerpts from /linux/README)
+
+
+- if a bug results in a message like
+
+	unable to handle kernel paging request at address C0000010
+	Oops: 0002
+	EIP:   0010:XXXXXXXX
+	eax: xxxxxxxx   ebx: xxxxxxxx   ecx: xxxxxxxx   edx: xxxxxxxx
+	esi: xxxxxxxx   edi: xxxxxxxx   ebp: xxxxxxxx
+	ds: xxxx  es: xxxx  fs: xxxx  gs: xxxx
+	Pid: xx, process nr: xx
+	xx xx xx xx xx xx xx xx xx xx
+
+  or similar kernel debugging information on your screen or in your
+  system log, please duplicate it *exactly*.  The dump may look
+  incomprehensible to you, but it does contain information that may
+  help debugging the problem.  The text above the dump is also
+  important: it tells something about why the kernel dumped code (in
+  the above example it's due to a bad kernel pointer)
+
+- in debugging dumps like the above, please look up what the EIP value 
+  means.  The hex value as such doesn't help me or anybody else very much: 
+  it will depend on your particular kernel setup.  What you should do is 
+  take the hex value from the EIP line (ignore the "0010:"), and look it up 
+  in the kernel namelist to see which kernel function contains the offending 
+  address.
+
+  To find out the kernel function name, you'll need to 
+
+         less /linux/System.map
+
+  This will give you a list of kernel addresses sorted in ascending
+  order, from which it is simple to find the function that contains the
+  offending address.  Note that the address given by the kernel
+  debugging messages will not necessarily match exactly with the
+  function addresses (in fact, that is very unlikely), so you can't
+  just 'grep' the list: the list will, however, give you the starting
+  point of each kernel function, so by looking for the function that
+  has a starting address lower than the one you are searching for but
+  is followed by a function with a higher address you will find the one
+  you want.  In fact, it may be [IS!] a good idea to include a bit of
+  "context" in your problem report, giving a few lines around the
+  interesting one. 
+
+  I included a small program which does this for you. Just call
+
+         grep_eip /linux/System.map address
+
+  for example: grep_eip /linux/System.map 182f98
+
+- alternately, you can use gdb on a running kernel. (read-only; i.e. you
+  cannot change values or set break points.) To do this, first compile the
+  kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
+  clean". You'll also need to enable CONFIG_PROC_FS (via "make config").
+
+  After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
+  You can now use all the usual gdb commands. The command to look up the
+  point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
+  with the EIP value.)
+
+  gdb'ing a non-running kernel currently fails because gdb (wrongly)
+  disregards the starting offset for which the kernel is compiled.
+
+
+
+If you can't solve a problem, send me
+
+- a description of the problem,
+- information on your hardware (computer system, scc board, modem)
+- your kernel version
+- the output of sccstat /dev/sc# ("#" is the No. of the channel)
+- the settings of "speed", "clock" and "mode" for that channel
+  in /etc/z8530drv.rc
+- your scc_config.h
+
+
+And always remember: 
+The 1.1.* kernel series is for alpha tests -- use at your own risk ;-)
+The 1.2.* series should run reliable. This driver perhaps NOT!
+The 1.3.* kernel series is for alpha tests again... you get the idea!
+
+------------
+
+Example scc_config.h
+
+#include <linux/scc.h>
+
+/********* CONFIGURATION PARAMATERES; PLEASE CHANGE THIS TO YOUR OWN SITUATION **********/
+
+/* SCC hardware parameters */
+
+/* use the following board types: 
+ *
+ *	PA0HZP		OptoSCC (PA0HZP)
+ *	EAGLE         	EAGLE
+ *	PC100         	PC100 
+ *	PRIMUS        	PRIMUS-PC (DG9BL)
+ *	DRSI          	DRSI PC*Packet
+ *	BAYCOM        	BayCom (U)SCC
+ *	
+ */
+
+int     Nchips	     = 2	; /* number of chips */
+io_port Vector_Latch = 0	; /* addr. of INTACK-Latch (0 for poll mode) */
+int     Ivec	     = 7	; /* interrupt vector */
+long    Clock	     = 4915200	; /* frequency of the scc clock */
+char	Board	     = BAYCOM	; /* what type of SCC card do you use? */
+int	Option	     = 0	; /* command for extra hardware */
+io_port Special_Port = 0	; /* port address for special hardware */
+				  /* (for EAGLE, PC100, PRIMUS, DRSI) */
+
+			/*      ^  never remove the semicolon !! */
+			
+
+
+/* 			Channel    A      B	    Chip	*/
+/*			         ============	  ========	*/
+/* Control ports:						*/
+
+io_port SCC_ctrl[MAXSCC * 2] = 	{0x304, 0x305,  /* ...one... 	*/
+				 0x306, 0x307,  /* ...two...	*/
+				     0,     0,  /* ...three...	*/
+				     0,     0}; /* ...four...	*/
+
+/* Data ports:							*/
+
+io_port SCC_data[MAXSCC * 2] =  {0x300, 0x301,	/* ...one...	*/
+				 0x302, 0x303,	/* ...two...	*/
+				     0,     0,	/* ...three...	*/
+				     0,     0};	/* ...four...	*/
+
+
+/* set to '1' if you have and want ESCC chip (8580/85180/85280) support */
+
+/*					      Chip	*/
+/*				            ========   	*/
+int SCC_Enhanced[MAXSCC] =	{0,	/* ...one...	*/
+				 0,  	/* ...two...	*/
+				 0,  	/* ...three...	*/
+				 0};	/* ...four...	*/
+
+/* some useful #defines. You might need them or not */
+
+#define VERBOSE_BOOTMSG 1
+#undef  SCC_DELAY		/* perhaps a 486DX2 is a *bit* too fast */
+#undef  SCC_LDELAY		/* slow it even a bit more down */
+#undef  DONT_CHECK		/* don't look if the SCCs you specified are available */
+
+
+/* The external clocking, nrz and fullduplex divider configuration is gone */
+/* you can set these parameters in /etc/z8530drv.rc and initialize the  */
+/* driver with sccinit */
+
+---------
+
+I still can't test the DRSI board, but this configuration derived from
+the PE1CHL SCC driver configuration should work:
+
+An example of scc_config.h for 
+
+One DRSI board installed:
+=========================
+
+/* gencfg 1 0x300 0x10 2 0 1 0 7 4915200 */
+
+/* file generated by $Id: gencfg.c,v 1.2 1994/11/29 21:42:24 JReuter Exp JReuter $ */
+
+#include <linux/scc.h>
+
+int     Nchips	     = 1;
+io_port Vector_Latch = 0x0;
+int     Ivec	     = 7;
+long    Clock	     = 4915200;
+char	Board	     = PA0HZP;
+int	Option	     = 0;
+io_port Special_Port = 0x0;
+
+io_port SCC_ctrl[MAXSCC * 2] =
+{0x302, 0x300, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0};
+
+io_port SCC_data[MAXSCC * 2] =
+{0x303, 0x301, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0};
+
+/* set to '1' if you have and want ESCC chip (8580/85180/85280) support */
+
+/*					      Chip	*/
+/*				            ========   	*/
+int SCC_Enhanced[MAXSCC] =	{0,	/* ...one...	*/
+				 0,  	/* ...two...	*/
+				 0,  	/* ...three...	*/
+				 0};	/* ...four...	*/
+
+#define VERBOSE_BOOTMSG 1
+#undef  SCC_DELAY		/* perhaps a 486DX2 is a *bit* too fast */
+#undef  SCC_LDELAY		/* slow it even a bit more down */
+#undef  DONT_CHECK		/* don't look if the SCCs you specified are available */
+
+
+
+Two boards installed:
+=====================
+
+/* file generated by $Id: gencfg.c,v 1.2 1994/11/29 21:42:24 JReuter Exp JReuter $ */
+
+#include <linux/scc.h>
+
+int     Nchips	     = 2;
+io_port Vector_Latch = 0x0;
+int     Ivec	     = 7;
+long    Clock	     = 4915200;
+char	Board	     = PA0HZP;
+int	Option	     = 0;
+io_port Special_Port = 0x0;
+
+io_port SCC_ctrl[MAXSCC * 2] =
+{0x302, 0x300, 0x312, 0x310, 0x0, 0x0, 0x0, 0x0};
+
+io_port SCC_data[MAXSCC * 2] =
+{0x303, 0x301, 0x313, 0x311, 0x0, 0x0, 0x0, 0x0};
+
+/* set to '1' if you have and want ESCC chip (8580/85180/85280) support */
+
+/*					      Chip	*/
+/*				            ========   	*/
+int SCC_Enhanced[MAXSCC] =	{0,	/* ...one...	*/
+				 0,  	/* ...two...	*/
+				 0,  	/* ...three...	*/
+				 0};	/* ...four...	*/
+
+#define VERBOSE_BOOTMSG 1
+#undef  SCC_DELAY		/* perhaps a 486DX2 is a *bit* too fast */
+#undef  SCC_LDELAY		/* slow it even a bit more down */
+#undef  DONT_CHECK		/* don't look if the SCCs you specified are available */
+
+
+
+
+
+*****************
+
+You  m u s t  use "clock dpll" in /etc/z8530drv.rc for operation, 
+the on-board baudrate generator is not supported.
+
+*****************
+(mni tnx to Mike Bilow)
+
+ 
+...an many thanks to Linus Torvalds and Alan Cox for including the driver
+   in the LinuX standard distribution...
+
+Joerg Reuter	ampr-net: [email protected]
+		AX-25   : DL1BKE @ DB0ACH.#NRW.DEU.EU
+		Internet: [email protected]

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of this