savecore(4)

NAME

savecore − description of a core dump directory format

DESCRIPTION

Location of Core Directory

The directory in which core dump information is stored can be specified as the dirname parameter to savecore. By default, the directory /var/adm/crash will be used as dirname by the startup script /sbin/init.d/savecore. User configurable options are located in the script /etc/rc.config.d/savecore.

Within this dump directory, savecore saves the core image and related files in the subdirectory dirname/core.n. The trailing n in the directory name is a number that increases by one each time savecore is run with the same dirname. This number is kept in the file dirname/bounds, which is created if it does not already exist.

By default, /stand/vmunix is used as the name of the kernel module saved by savecore. If /stand/vmunix was not the running kernel at the time of the crash, the -d option should be used to specify the kernel.

The (obsolescent) file dirname/minfree contains the amount of free space (in 512-byte blocks) that must remain free for ordinary user files after savecore completes.

Contents of Core Directory

• One or more files named core.n .xxxx , where xxxx is a decimal integer. The integer will be as many digits as necessary to accommodate the highest numbered file. These files contain a contiguous portion of physical memory from the dump. Some portion of the file may be zeroes if one or more of the physical pages could not be dumped. The files are broken into equal size chunks (except for possibly the last file). The chunk size is chosen by the user through the savecore -s option.

• A file for the kernel module (e.g., /stand/vmunix) that was loaded at dump time. Typically, this file will be called vmunix.

• A text file called INDEX, which contains information about the dump (see below).

With the exception of INDEX, any of the files in this directory may be compressed. If so, they will carry a .gZ or .Z suffix (depending on the compression program used), and must be uncompressed before use. Most common debuggers will be able to uncompress these files automatically as needed.

INDEX File Format

The INDEX file is the reference to all other files in the dump directory. This file will contain lines with the following keywords:

#, comment This line should be ignored.

error Any errors printed by savecore while it saved this dump. This allows debuggers to repeat the warnings for the user reviewing the dump. Errors are not necessarily fatal.

warning All warnings printed by savecore while it recorded this dump directory are also saved in the INDEX file. This allows debuggers to repeat the warnings for the user reviewing the dump.

hostname The name of the machine on which savecore was run. If savecore is recovering a dump from tape, the hostname will be that of the system that recorded the tape.

modelname The model name of the machine on which savecore was run. If savecore is recovering a dump from tape, the model name will be that of the system that recorded the tape.

panic The panic string.

dumptime The date and time of the dump.

savetime The date and time savecore ran. If savecore is restoring a dump from tape, this is the time the restore ran, not the time the tape was written.

release The release version string of the system that dumped.

memsize The size in bytes of physical memory in the system that dumped. (This is the total memory size, regardless of how much of it could fit in the dump device.)

chunksize The uncompressed size in bytes of the individual image files, except perhaps the last one.

module Each kernel module has a corresponding line in the INDEX file. These lines have the following fields:

pathname The complete pathname of the module as stored in the dump.

filename The name of the file in the dump directory (including any .2, .3 etc. added to make it unique), or " − " if the module was unavailable at savecore time.

loadaddr The dm_load_address value for the dump header for the module, in hexadecimal.

ident The dm_ident value from the dump header for this module, in hexadecimal.

size The size of the file, in bytes.

checksum The checksum of the file, as computed by cksum(1) at savecore time.

chunk Each physical memory chunk (see chunksize, above) has a corresponding line in the INDEX file. These lines have the following fields:

address Each physical memory address (hexadecimal) of the first byte in the chunk.

size The number of bytes in the chunk (hexadecimal).

filename The name of the image file in the dump directory, or " − " if the physical memory for that chunk is not available.

checksum The checksum of the image chunk, as computed by cksum(1).

Example INDEX File

comment     savecore core dump INDEX file
hostname    hpacct2
modelname   9000/730
panic       (display==0xb800, flags==0x0) Data page fault
dumptime    Tue Dec 6 09:45:15 PST 1994
savetime    Tue Dec 6 09:52:12 PST 1994
release     @(#)B2352A HP-UX (B.10.10) #1: Thu Nov 3 02:22:24 PST 1994
memsize     67108864
chunksize   16777216
module      /stand/vmunix vmunix 0x0000000012345678 0x0000000000000000
            6553600 829572784
chunk       0x0000000000000000 0x0000000001000000 core.1.0 771598417
chunk       0x0000000001000000 0x0000000001000000 core.1.1 459832781
chunk       0x0000000002000000 0x0000000000450000 core.1.2 227914648
warning     Insufficient space to save full core dump:
chunk       0x0000000002450000 0x0000000001bb0000 - 0
warning     only 38076416 of 67108864 bytes saved.

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