diff options
author | Joel Sherrill <joel@rtems.org> | 2016-03-22 17:58:42 -0500 |
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committer | Joel Sherrill <joel@rtems.org> | 2016-03-24 11:41:23 -0500 |
commit | eaf03e9f17d8d12afecf8eb9cac2f0dc37dd9009 (patch) | |
tree | 52d27a786f4d9969e42a90018ad71ca5233feeac | |
parent | shell/hexdump-odsyntax.c: Add define of _GNU_SOURCE to avoid warnings (diff) | |
download | rtems-eaf03e9f17d8d12afecf8eb9cac2f0dc37dd9009.tar.bz2 |
pc386/README: Replace contents with discussion of console/printk device selection
-rw-r--r-- | c/src/lib/libbsp/i386/pc386/README | 116 |
1 files changed, 59 insertions, 57 deletions
diff --git a/c/src/lib/libbsp/i386/pc386/README b/c/src/lib/libbsp/i386/pc386/README index f49f7420e4..bfebf1951c 100644 --- a/c/src/lib/libbsp/i386/pc386/README +++ b/c/src/lib/libbsp/i386/pc386/README @@ -1,60 +1,62 @@ # # This board support package works with a target PC # -# Decisions to be made a link-edit time are: -# - The size of the memory allocator heap. The default value is -# 64 kbytes. If the network package is used the heap -# should be at least 256 kbytes. If your network is large, or -# busy, the heap should be even larger. -# To choose a heap size of 256 kbytes, -# CFLAGS_LD += -Wl,--defsym -Wl,HeapSize=0x40000 - -BSP NAME: pc386 -BOARD: PC -BUS: none -CPU FAMILY: 386, 486, 586, 686 -COPROCESSORS: none -MODE: not applicable - -DEBUG MONITOR: - -PERIPHERALS -=========== -TIMERS: 8254 Programmable Interval Timer -RESOLUTION: -SERIAL PORTS: COM1, COM2 -REAL-TIME CLOCK: -DMA: -VIDEO: VGA -SCSI: -NETWORKING: external Ethernet controller based on WD8003. - -DRIVER INFORMATION -================== -CLOCK DRIVER: 8254 Programmable Interval Timer -IOSUPP DRIVER: -SHMSUPP: -TIMER DRIVER: - -STDIO -===== -PORT: -ELECTRICAL: -BAUD: -BITS PER CHARACTER: -PARITY: -STOP BITS: - -NOTES -===== - -Board description ------------------ -clock rate: -bus width: -ROM: -RAM: - -Host System ------------ -Linux + +This BSP supports a standard Intel/AMD PC on i386 and up CPUs. If on +a Pentium or above, the TSC register is used for timing calibration +purposes rather than relying entirely on the i8254. + +Partial support is implemented for more modern PCs which do not have +a complete complement of legacy peripherals. + +Console/Printk Device Selection +=============================== +The pc386 console device driver supports a variety of devices +including the VGA/keyboard and a number of serial ports. The +default console is selected based on which devices are present +in the following order of priority: + ++ VGA and keyboard ++ COM1 through COM4aaa + ++ Any COM devices on the PCI bus + +Beyond the dynamic probing for device presence, a combination of +configure and boot time options are available. By default, all devices +are enabled. The configure time options are: + ++ BSP_ENABLE_VGA - value of 1 to enable, 0 to disable ++ BSP_ENABLE_COM1_COM4 - value of 1 to enable, 0 to disable ++ BSP_USE_COM1_AS_CONSOLE - value of 1 forces console to COM1 + +An example of using these to force the console to COM1 is: + +../rtems/configure --target=i386-rtems4.12 \ + USE_COM1_AS_CONSOLE=1 --enable-rtemsbsp=pc386 \ + ... other arguments ... + +The --console and --printk options can be used to specify the +device associated with stdin, stdout, and stderr as well as +the device associated with kernel debug IO (e.g. printk()/getk()). +Both take the name of a device without the "/dev/" prefix. + +The --console argument is interpreted first and assumed to +specify the console and kernel debug IO device. The --printk +is then interpreted to specify the debug kernel IO device. +For example, + +--console=com1 --printk=vgacons + +specifies that com1 is to be used for stdin, stdout, and stderr +while the VGA console is to be used for kernel debug IO. +Note that the lower case com1 is intentional as this maps to +the RTEMS device /dev/com1. + +The device name may be followed by a baud rate. The following +example illustrates this: + +--console=com1,19200 --printk=vgacons + +If the specified device is not present, then a suitable fallback +device is selected. The fallback order is based upon the probe +order listed earlier. |