Книга: Embedded Linux Primer: A Practical, Real-World Approach

5.1.4. Boot Messages

5.1.4. Boot Messages

Perhaps you've seen a PC workstation booting a desktop Linux distribution such as Red Hat or SUSE Linux. After the PC's own BIOS messages, you see a flurry of console messages being displayed by Linux as it initializes the various kernel subsystems. Significant portions of the output are common across disparate architectures and machines. Two of the more interesting early boot messages are the kernel version string and the kernel command line, which is detailed shortly. Listing 5-3 reproduces the kernel boot messages for the ADI Engineering Coyote Reference Platform booting Linux on the Intel XScale IXP425 processor. The listing has been formatted with line numbers for easy reference.

Listing 5-3. Linux Boot Messages on IPX425

1 Uncompressing Linux... done, booting the kernel.
2 Linux version 2.6.14-clh (chris@pluto) (gcc version 3.4.3 (MontaVista 3.4.3-25.0.30.0501131 2005-07-23)) #11 Sat Mar 25 11:16:33 EST 2006
3 CPU: XScale-IXP42x Family [690541c1] revision 1 (ARMv5TE)
4 Machine: ADI Engineering Coyote
5 Memory policy: ECC disabled, Data cache writeback
6 CPU0: D VIVT undefined 5 cache
7 CPU0: I cache: 32768 bytes, associativity 32, 32 byte lines, 32 sets
8 CPU0: D cache: 32768 bytes, associativity 32, 32 byte lines, 32 sets
9 Built 1 zonelists
10 Kernel command line: console=ttyS0,115200 ip=bootp root=/dev/nfs
11 PID hash table entries: 512 (order: 9, 8192 bytes)
12 Console: colour dummy device 80x30
13 Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
14 Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
15 Memory: 64MB = 64MB total
16 Memory: 62592KB available (1727K code, 339K data, 112K init)
17 Mount-cache hash table entries: 512
18 CPU: Testing write buffer coherency: ok
19 softlockup thread 0 started up.
20 NET: Registered protocol family 16
21 PCI: IXP4xx is host
22 PCI: IXP4xx Using direct access for memory space
23 PCI: bus0: Fast back to back transfers enabled
24 dmabounce: registered device 0000:00:0f.0 on pci bus
25 NetWinder Floating Point Emulator V0.97 (double precision)
26 JFFS2 version 2.2. (NAND) (C) 2001-2003 Red Hat, Inc.
27 Serial: 8250/16550 driver $Revision: 1.90 $ 2 ports, IRQ sharing disabled
28 ttyS0 at MMIO 0xc8001000 (irq = 13) is a XScale
29 io scheduler noop registered
30 io scheduler anticipatory registered
31 io scheduler deadline registered
32 io scheduler cfq registered
33 RAMDISK driver initialized: 16 RAM disks of 8192K size 1024 blocksize
34 loop: loaded (max 8 devices)
35 eepro100.c:v1.09j-t 9/29/99 Donald Becker http://www.scyld.com/network/eepro100.html
36 eepro100.c: $Revision: 1.36 $ 2000/11/17 Modified by Andrey V. Savochkin <[email protected]> and others
37 eth0: 0000:00:0f.0, 00:0E:0C:00:82:F8, IRQ 28.
38   Board assembly 741462-016, Physical connectors present: RJ45
39   Primary interface chip i82555 PHY #1.
40   General self-test: passed.
41   Serial sub-system self-test: passed.
42   Internal registers self-test: passed.
43   ROM checksum self-test: passed (0x8b51f404).
44 IXP4XX-Flash.0: Found 1 x16 devices at 0x0 in 16-bit bank
45 Intel/Sharp Extended Query Table at 0x0031
46 Using buffer write method
47 cfi_cmdset_0001: Erase suspend on write enabled
48 Searching for RedBoot partition table in IXP4XX-Flash.0 at offset 0xfe0000
49 5 RedBoot partitions found on MTD device IXP4XX-Flash.0
50 Creating 5 MTD partitions on "IXP4XX-Flash.0":
51 0x00000000-0x00060000 : "RedBoot"
52 0x00100000-0x00260000 : "MyKernel"
53 0x00300000-0x00900000 : "RootFS"
54 0x00fc0000-0x00fc1000 : "RedBoot config"
55 mtd: partition "RedBoot config" doesn't end on an erase block -- force read-only0x00fe0000-0x01000000 : "FIS directory"
56 NET: Registered protocol family 2
57 IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
58 TCP established hash table entries: 4096 (order: 2, 16384 bytes)
59 TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
60 TCP: Hash tables configured (established 4096 bind 4096)
61 TCP reno registered
62 TCP bic registered
63 NET: Registered protocol family 1
64 Sending BOOTP requests . OK
65 IP-Config: Got BOOTP answer from 192.168.1.10, my address is 192.168.1.141
66 IP-Config: Complete:
67        device=eth0, addr=192.168.1.141, mask=255.255.255.0, gw=255.255.255.255,
68        host=192.168.1.141, domain=, nis-domain=(none),
69        bootserver=192.168.1.10, rootserver=192.168.1.10, rootpath=/home/chris/sandbox/coyote-target
70 Looking up port of RPC 100003/2 on 192.168.1.10
71 Looking up port of RPC 100005/1 on 192.168.1.10
72 VFS: Mounted root (nfs filesystem).
73 Freeing init memory: 112K
74 Mounting proc
75 Starting system loggers
76 Configuring lo
77 Starting inetd
78 / #

The kernel produces much useful information during startup, as shown in Listing 5-3. We study this output in some detail in the next few sections. Line 1 is produced by the bootstrap loader we presented earlier in this chapter. This message was produced by the decompression loader found in …/arch/arm/boot/compressed/misc.c.

Line 2 of Listing 5-3 is the kernel version string. It is the first line of output from the kernel itself. One of the first lines of C code executed by the kernel (in .../init/main.c) upon entering start_kernel() is as follows:

printk(linux_banner);

This line produces the output just describedthe kernel version string, Line 2 of Listing 5-3. This version string contains a number of pertinent data points related to the kernel image:

• Kernel version: Linux version 2.6.10-clh

• Username/machine name where kernel was compiled

• Toolchain info: gcc version 3.4.3, supplied by MontaVista Software

• Build number

• Date and time compiled

This is useful information both during development and later in production. All but one of the entries are self-explanatory. The build number is simply a tool that the developers added to the version string to indicate that something more substantial than the date and time changed from one build to the next. It is a way for developers to keep track of the build in a generic and automatic fashion. You will notice in this example that this was the eleventh build in this series, as indicated by the #11 on line 2 of Listing 5-3. The version string is stored in a hidden file in the top-level Linux directory and is called .version. It is automatically incremented by a build script found in .../scripts/mkversion and by the top-level makefile. In short, it is a version string that is automatically incremented whenever anything substantial in the kernel is rebuilt.

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