Changeset eaf03e9f in rtems


Ignore:
Timestamp:
Mar 22, 2016, 10:58:42 PM (3 years ago)
Author:
Joel Sherrill <joel@…>
Branches:
master
Children:
77c0135
Parents:
85f6901
git-author:
Joel Sherrill <joel@…> (03/22/16 22:58:42)
git-committer:
Joel Sherrill <joel@…> (03/24/16 16:41:23)
Message:

pc386/README: Replace contents with discussion of console/printk device selection

File:
1 edited

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  • c/src/lib/libbsp/i386/pc386/README

    r85f6901 reaf03e9f  
    22# This board support package works with a target PC
    33#
    4 # Decisions to be made a link-edit time are:
    5 #     - The size of the memory allocator heap.  The default value is
    6 #       64 kbytes.  If the network package is used the heap
    7 #       should be at least 256 kbytes.  If your network is large, or
    8 #       busy, the heap should be even larger.
    9 #       To choose a heap size of 256 kbytes,
    10 #       CFLAGS_LD += -Wl,--defsym -Wl,HeapSize=0x40000
    114
    12 BSP NAME:           pc386
    13 BOARD:              PC
    14 BUS:                none
    15 CPU FAMILY:         386, 486, 586, 686
    16 COPROCESSORS:       none
    17 MODE:               not applicable
     5This BSP supports a standard Intel/AMD PC on i386 and up CPUs. If on
     6a Pentium or above, the TSC register is used for timing calibration
     7purposes rather than relying entirely on the i8254.
    188
    19 DEBUG MONITOR:     
     9Partial support is implemented for more modern PCs which do not have
     10a complete complement of legacy peripherals.
    2011
    21 PERIPHERALS
    22 ===========
    23 TIMERS:             8254 Programmable Interval Timer
    24 RESOLUTION:         
    25 SERIAL PORTS:       COM1, COM2
    26 REAL-TIME CLOCK:
    27 DMA:               
    28 VIDEO:              VGA
    29 SCSI:               
    30 NETWORKING:         external Ethernet controller based on WD8003.
     12Console/Printk Device Selection
     13===============================
     14The pc386 console device driver supports a variety of devices
     15including the VGA/keyboard and a number of serial ports. The
     16default console is selected based on which devices are present
     17in the following order of priority:
    3118
    32 DRIVER INFORMATION
    33 ==================
    34 CLOCK DRIVER:       8254 Programmable Interval Timer
    35 IOSUPP DRIVER:     
    36 SHMSUPP:           
    37 TIMER DRIVER:       
     19+ VGA and keyboard
     20+ COM1 through COM4aaa
    3821
    39 STDIO
    40 =====
    41 PORT:               
    42 ELECTRICAL:         
    43 BAUD:               
    44 BITS PER CHARACTER:
    45 PARITY:             
    46 STOP BITS:         
     22+ Any COM devices on the PCI bus
    4723
    48 NOTES
    49 =====
     24Beyond the dynamic probing for device presence, a combination of
     25configure and boot time options are available. By default, all devices
     26are enabled. The configure time options are:
    5027
    51 Board description
    52 -----------------
    53 clock rate:     
    54 bus width:     
    55 ROM:           
    56 RAM:           
     28+ BSP_ENABLE_VGA - value of 1 to enable, 0 to disable
     29+ BSP_ENABLE_COM1_COM4 - value of 1 to enable, 0 to disable
     30+ BSP_USE_COM1_AS_CONSOLE - value of 1 forces console to COM1
    5731
    58 Host System
    59 -----------
    60 Linux
     32An example of using these to force the console to COM1 is:
     33
     34../rtems/configure --target=i386-rtems4.12 \
     35  USE_COM1_AS_CONSOLE=1 --enable-rtemsbsp=pc386 \
     36  ... other arguments ...
     37
     38The --console and --printk options can be used to specify the
     39device associated with stdin, stdout, and stderr as well as
     40the device associated with kernel debug IO (e.g. printk()/getk()).
     41Both take the name of a device without the "/dev/" prefix.
     42
     43The --console argument is interpreted first and assumed to
     44specify the console and kernel debug IO device. The --printk
     45is then interpreted to specify the debug kernel IO device.
     46For example,
     47
     48--console=com1 --printk=vgacons
     49
     50specifies that com1 is to be used for stdin, stdout, and stderr
     51while the VGA console is to be used for kernel debug IO.
     52Note that the lower case com1 is intentional as this maps to
     53the RTEMS device /dev/com1.
     54
     55The device name may be followed by a baud rate. The following
     56example illustrates this:
     57
     58--console=com1,19200 --printk=vgacons
     59
     60If the specified device is not present, then a suitable fallback
     61device is selected. The fallback order is based upon the probe
     62order listed earlier.
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