Re: serial console on x86

From: Richard B. Johnson (root_at_chaos.analogic.com)
Date: 09/04/03

  • Next message: Antonio Vargas: "How to get a backtrace (sysrq-t) on a specific task?" 
    Date:	Thu, 4 Sep 2003 14:03:30 -0400 (EDT)
To: David Lang <david.lang@digitalinsight.com>

    On Thu, 4 Sep 2003, David Lang wrote:

    > On Thu, 4 Sep 2003, Richard B. Johnson wrote:
    >
    > > On Thu, 4 Sep 2003, David Lang wrote:
    > >
    > > > I am attempting to install linux (debian 3 based) on some dual athlon
    > > > boxes with no video card. The BIOS does include serial console
    > > > capabilities
    > > >
    > > > once the system is installed I have no problem booting from the hard
    > > > drive, but when I attempt to boot from a CD to install (ISOLINUX custom
    > > > boot disk) I see the lilo prompt, the loading kernel message, the loading
    > > > initrd.gz message and then it prints 'Ready.' and reboots the same
    > > > bootdisk will work just fine if I install a video card in the machine (and
    > > > the same kernel with lilo boots just fine without a video card after it
    > > > gets installed)
    > > >
    > > > any ideas why the kernel may crash before printing any messages in this
    > > > situation? I've tried this with 2.4.17 and 2.4.22 with the exact same
    > > > results.
    > > >
    > > > David Lang
    > >
    > > append="console=ttyS0,9600"
    > > ... in the lilo configuration works fine in the exact same kernels
    > > you cite. However, the CD install does not have the console changed
    > > so it will probably not work. The BIOS is never used past the point
    > > where the OS is physically loaded so it makes no difference
    > > if you have "serial console capabilities" in the BIOS.
    >
    > I have a similar line in the lilo configuration. if there is a video card
    > in the system this works and I see the kernel boot over the serial port,
    > if there is not a video card it reboots instead of running the kernel.
    >
    > David Lang

    Well I have a system sitting in the lab. On one machine that
    was already up, I did cat /dev/ttyS0 >xxx.xxx. The other machine,
    which was connected to the serial port, I booted without a screen
    card. This system boots off a NVRAM disk, which is installed
    by the BIOS as a floppy drive so the machine "thinks" it's booting
    a floppy.

                            Analogic AMD-SC520 BIOS
                      Copyright(c) 2000-2003 Analogic Corporation

    Check screen memory.... failed
    Check ROM checksum .... okay 001C3E00
    Checking CMOS timer ... okay 01
    Checking main timer ... okay 3578
    Checking timer 2 ...... okay A804
    Check PCI devices ..... 30001022 000010E3 8000104C 20001022
    Check FDC operation ... okay 0000
    Check virtual mode .... okay 0000
    Check extended RAM .... okay 32505856 bytes
    System RAM found ...... 640 Kilobytes
    Extended RAM found .... 31744 Kilobytes
    Printer ports found ... 0278
    RS-232C ports found ... 03F8 02F8 03E8 02E8
    CMOS time ............. 13:36:32 09-04-2003
    Math coprocessor ...... found
    ROM module scan ....... D000 Copyright(c) 1999 - 2003, Analogic Corporation.
    All rights reserved worldwide.
    NVRAM Ramdisk driver, version 1.2
    okay
    Booting .....

    LILO Loading Message-Based

    Linux version 2.4.22 (root@chaos) (gcc version egcs-2.91.66 19990314 (egcs-1.1.2 release)) #7 SMP Fri Aug 29 08:24:45 EDT 2003
    BIOS-provided physical RAM map:
     BIOS-e801: 0000000000000000 - 000000000009f000 (usable)
     BIOS-e801: 0000000000100000 - 0000000002000000 (usable)
    32MB LOWMEM available.
    On node 0 totalpages: 8192
    zone(0): 4096 pages.
    zone(1): 4096 pages.
    zone(2): 0 pages.
    DMI not present.
    Kernel command line: auto BOOT_IMAGE=Message-Based root=100
    No local APIC present or hardware disabled
    Initializing CPU#0
    Calibrating delay loop... 66.90 BogoMIPS
    Memory: 30064k/32768k available (899k kernel code, 2316k reserved, 211k data, 88k init, 0k highmem)
    Checking if this processor honours the WP bit even in supervisor mode... Ok.
    Dentry cache hash table entries: 4096 (order: 3, 32768 bytes)
    Inode cache hash table entries: 2048 (order: 2, 16384 bytes)
    Mount cache hash table entries: 512 (order: 0, 4096 bytes)
    Buffer cache hash table entries: 1024 (order: 0, 4096 bytes)
    Page-cache hash table entries: 8192 (order: 3, 32768 bytes)
    Checking 'hlt' instruction... OK.
    POSIX conformance testing by UNIFIX
    CPU0: AMD 486 DX/4-WB stepping 04
    SMP motherboard not detected.
    Local APIC not detected. Using dummy APIC emulation.
    Waiting on wait_init_idle (map = 0x0)
    All processors have done init_idle
    PCI: Using configuration type 1
    PCI: Probing PCI hardware
    PCI: Probing PCI hardware (bus 00)
    Linux NET4.0 for Linux 2.4
    Based upon Swansea University Computer Society NET3.039
    Initializing RT netlink socket
    Starting kswapd
    i2c-core.o: i2c core module
    i2c-algo-bit.o: i2c bit algorithm module
    pty: 256 Unix98 ptys configured
    Serial driver version 5.05c (2001-07-08) with MANY_PORTS SHARE_IRQ SERIAL_PCI enabled
    ttyS00 at 0x03f8 (irq = 4) is a 16550A
    ttyS01 at 0x02f8 (irq = 3) is a 16550A
    Floppy drive(s): fd0 is 1.44M
    FDC 0 is a National Semiconductor PC87306
    RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
    NET4: Linux TCP/IP 1.0 for NET4.0
    IP Protocols: ICMP, UDP, TCP
    IP: routing cache hash table of 512 buckets, 4Kbytes
    TCP: Hash tables configured (established 2048 bind 2048)
    NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
    RAMDISK: Compressed image found at block 0
    Freeing initrd memory: 217k freed
    VFS: Mounted root (ext2 filesystem) readonly.
    Freeing unused kernel memory: 88k freed
    Warning: unable to open an initial console.

    Analogic(tm) VXI/Bus Driver : initialization complete
    [SNIPPED...]
    My 'init' gets control and loads modules.....

    The message from the BIOS states that there was no screen memory
    so the BIOS automatically uses the RS-232C port(s) for messages.
    You can see the message from the kernel that it failed to
    open an initial console. My init closes 0, 1, and 2 then tries
    to open the console. If that fails, it opens ttyS0 instead and
    dups() the fds. That way, it doesn't rely upon the lilo commands.

    You can see all this working with linux-2.4.22. It it doesn't
    work on your system, something else is broken. I would turn
    OFF the BIOS screen emulation first and see if that fixes it.
    You won't see the BIOS messages, but you should see the kernel
    messages once it starts.

    Cheers,
    *** Johnson
    Penguin : Linux version 2.4.22 on an i686 machine (794.73 BogoMips).
                Note 96.31% of all statistics are fiction.

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