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### Specify Xen physical start address for x86_64

Source: https://www.linux.org/docs/man8/makedumpfile.html

On x86_64 systems, specify the Xen physical start address if the Xen code/data is relocatable and not present in CRASHINFO. This address can be found in /proc/iomem.

```bash
# makedumpfile -E -X --xen_phys_start 0xcee00000 /proc/vmcore dumpfile
```

--------------------------------

### Rearrange Flattened Dump Data with Perl Script

Source: https://www.linux.org/docs/man8/makedumpfile.html

The makedumpfile-R.pl script can rearrange flattened dump data to a normal DUMPFILE on a remote host, even if makedumpfile is not installed there. This is an alternative to the -R option.

```bash
# makedumpfile -F -d 31 -x vmlinux /proc/vmcore \
| ssh user@host "makedumpfile-R.pl dumpfile"
```

--------------------------------

### Help and Version

Source: https://www.linux.org/docs/man8/makedumpfile.html

Displays help information or the version of makedumpfile.

```bash
makedumpfile -h
```

```bash
makedumpfile -v
```

--------------------------------

### Show help message and LZO/snappy support

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use -h or --help to display the help message and the status of LZO/snappy compression support.

```bash
-h (--help)
```

--------------------------------

### Basic makedumpfile Usage

Source: https://www.linux.org/docs/man8/makedumpfile.html

Creates a compressed dump file from VMCORE, optionally excluding pages based on VMLINUX or VMCOREINFO.

```bash
makedumpfile [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMPFILE
```

--------------------------------

### Create Compressed Dump File with Filtering

Source: https://www.linux.org/docs/man8/makedumpfile.html

Creates a compressed dump file (dump_level 3) from /proc/vmcore and saves it as dumpfile.1. Then, it creates a larger dump file (dump_level 31) from dumpfile.1, demonstrating file size reduction.

```bash
# makedumpfile -c -d 3 /proc/vmcore dumpfile.1
# makedumpfile -c -d 31 dumpfile.1 dumpfile.2
```

--------------------------------

### Show memory usage for x86_64

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use --mem-usage on x86_64 systems to display page numbers for different memory uses. This requires specifying /proc/kcore.

```bash
# makedumpfile --mem-usage /proc/kcore
```

--------------------------------

### Retry Dump Creation on Disk Full

Source: https://www.linux.org/docs/man8/makedumpfile.html

Attempts to create a dump file with dump_level 11. If it fails due to 'No space on device', it retries with dump_level 31. Requires the vmlinux file.

```bash
# makedumpfile -d 11,31 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Xen Dump File Creation

Source: https://www.linux.org/docs/man8/makedumpfile.html

Creates a dump file for Xen environments, optionally using Xen-specific symbols or VMCOREINFO.

```bash
makedumpfile [OPTION] [--xen-syms XEN-SYMS|--xen-vmcoreinfo VMCOREINFO] VMCORE DUMPFILE
```

--------------------------------

### Specify VMCOREINFO for Analysis

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use the -i option to specify VMCOREINFO instead of VMLINUX for analyzing the first kernel's memory usage. VMCOREINFO must be generated beforehand using the -g option.

--------------------------------

### Assemble multiple VMCOREs into a single DUMPFILE

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use --diskset to specify multiple VMCOREs from a diskset configuration. These will be assembled into a single DUMPFILE.

```bash
# makedumpfile -x vmlinux --diskset=vmcore1 --diskset=vmcore2 dumpfile
```

--------------------------------

### Splitting Dump Files

Source: https://www.linux.org/docs/man8/makedumpfile.html

Creates multiple smaller dump files from a single VMCORE, useful for systems with limited storage.

```bash
makedumpfile --split [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE DUMPFILE1 DUMPFILE2 [DUMPFILE3 ..]
```

--------------------------------

### Show makedumpfile version

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use the -v option to display the version of the makedumpfile utility.

```bash
-v
```

--------------------------------

### Diskset Option

Source: https://www.linux.org/docs/man8/makedumpfile.html

Specifies multiple diskset options for dump file creation.

```bash
makedumpfile [OPTION] -x VMLINUX --diskset=VMCORE1 --diskset=VMCORE2 [--diskset=VMCORE3 ..] DUMPFILE
```

--------------------------------

### Specify Kernel VMLINUX for Analysis

Source: https://www.linux.org/docs/man8/makedumpfile.html

The -x option specifies the VMLINUX file with debug information for analyzing the first kernel's memory usage. This is required when VMCORE does not contain VMCOREINFO and dump_level is 2 or more.

```bash
# makedumpfile -d 31 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Specify Xen symbols for analyzing Xen memory usage

Source: https://www.linux.org/docs/man8/makedumpfile.html

Provide the path to Xen symbols with debug information to analyze Xen's memory usage. This is not needed if VMCOREINFO for Xen is present.

```bash
# makedumpfile -E -X /proc/vmcore dumpfile
```

--------------------------------

### Compress Dump Data with zlib

Source: https://www.linux.org/docs/man8/makedumpfile.html

Compresses dump data using zlib (-c) and filters pages based on dump_level 31. Requires the vmlinux file for analysis and outputs to dumpfile.

```bash
# makedumpfile -c -d 31 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Threaded Dump File Creation

Source: https://www.linux.org/docs/man8/makedumpfile.html

Specifies the number of threads to use for creating the dump file.

```bash
makedumpfile [OPTION] [-x VMLINUX|-i VMCOREINFO] --num-threads THREADNUM VMCORE DUMPFILE
```

--------------------------------

### Create ELF Format Dump File

Source: https://www.linux.org/docs/man8/makedumpfile.html

Creates a dump file in ELF format with dump_level 31, filtering pages and using the vmlinux file. This option cannot be used with compression flags (-c, -l, -p).

```bash
# makedumpfile -E -d 31 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Full Dump File Extraction

Source: https://www.linux.org/docs/man8/makedumpfile.html

Extracts the full VMCORE content without modification, useful for specific scenarios.

```bash
makedumpfile -F [OPTION] [-x VMLINUX|-i VMCOREINFO] VMCORE
```

--------------------------------

### Extracting VMCOREINFO

Source: https://www.linux.org/docs/man8/makedumpfile.html

Generates VMCOREINFO from VMLINUX, which contains kernel information for makedumpfile.

```bash
makedumpfile -g VMCOREINFO -x VMLINUX
```

--------------------------------

### Reassemble multiple DUMPFILEs

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use this command to reassemble multiple DUMPFILEs that were created using the --split option back into a single DUMPFILE.

```bash
# makedumpfile --reassemble dumpfile1 dumpfile2 dumpfile
```

--------------------------------

### Specify splitblock size for --split analysis

Source: https://www.linux.org/docs/man8/makedumpfile.html

Set the splitblock size in kilobytes for analysis when using the --split option. This controls the maximum size difference between split dump files.

```bash
# makedumpfile --splitblock-size 1024 -d 31 -x vmlinux --split /proc/vmcore dumpfile1 dumpfile2
```

--------------------------------

### Filtering Dump Files with Configuration

Source: https://www.linux.org/docs/man8/makedumpfile.html

Uses a filter configuration file to exclude specific kernel data from the dump.

```bash
makedumpfile [OPTION] -x VMLINUX [--config FILTERCONFIGFILE] [--eppic EPPICMACRO] VMCORE DUMPFILE
```

--------------------------------

### Specify cyclic buffer size for bitmap data

Source: https://www.linux.org/docs/man8/makedumpfile.html

Configure the buffer size in kilobytes for bitmap data when generating a DUMPFILE. This can affect filtering processing cycles and working speed.

```bash
# makedumpfile --cyclic-buffer 1024 -d 31 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Specify working directory for temporary bitmap file

Source: https://www.linux.org/docs/man8/makedumpfile.html

Define a working directory for temporary bitmap files. This can improve filtering speed by avoiding saving the bitmap in memory.

```bash
# makedumpfile --work-dir /tmp -d 31 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Reassembling Split Dump Files

Source: https://www.linux.org/docs/man8/makedumpfile.html

Combines multiple split dump files back into a single DUMPFILE.

```bash
makedumpfile --reassemble DUMPFILE1 DUMPFILE2 [DUMPFILE3 ..] DUMPFILE
```

--------------------------------

### Re-creating Dump File

Source: https://www.linux.org/docs/man8/makedumpfile.html

Re-creates a dump file, potentially for reassembly or format conversion.

```bash
makedumpfile -R DUMPFILE
```

--------------------------------

### Extract dmesg log from VMCORE

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use --dump-dmesg to extract the dmesg log from a VMCORE. Specify -x VMLINUX or -i VMCOREINFO if the VMCORE lacks dmesg information.

```bash
# makedumpfile --dump-dmesg /proc/vmcore dmesgfile
# makedumpfile --dump-dmesg -x vmlinux /proc/vmcore dmesgfile
```

--------------------------------

### Print debugging message

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use the -D option to print debugging messages during makedumpfile execution.

```bash
-D
```

--------------------------------

### Overwrite Existing Dump File

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use the -f option to force overwriting an existing DUMPFILE. This is useful when you need to create a new dump and do not want to be prompted or stopped if the file already exists.

```bash
# makedumpfile -f -d 31 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Output Dump Data in Flattened Format via SSH

Source: https://www.linux.org/docs/man8/makedumpfile.html

The -F option outputs dump data in a flattened format suitable for transport over SSH. The subsequent command on the remote host processes this data.

```bash
# makedumpfile -F -c -d 31 -x vmlinux /proc/vmcore \
| ssh user@host "cat > dumpfile.tmp"
```

```bash
# makedumpfile -F -c -d 31 -x vmlinux /proc/vmcore \
| ssh user@host "makedumpfile -R dumpfile"
```

```bash
# makedumpfile -F -E -d 31 -i vmcoreinfo  /proc/vmcore \
| ssh user@host "makedumpfile -R dumpfile"
```

```bash
# makedumpfile -F -E --xen-vmcoreinfo VMCOREINFO /proc/vmcore \
| ssh user@host "makedumpfile -R dumpfile"
```

--------------------------------

### Dumping dmesg

Source: https://www.linux.org/docs/man8/makedumpfile.html

Extracts the kernel's dmesg log into a specified file.

```bash
makedumpfile --dump-dmesg [-x VMLINUX|-i VMCOREINFO] VMCORE LOGFILE
```

--------------------------------

### Avoid using mmap(2) for reading VMCORE

Source: https://www.linux.org/docs/man8/makedumpfile.html

Use this option to prevent makedumpfile from using mmap(2) when reading the VMCORE, primarily for debugging purposes.

```bash
# makedumpfile --non-mmap -d 31 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Filter Dump Data with Specific Dump Level

Source: https://www.linux.org/docs/man8/makedumpfile.html

Filters dump data by excluding pages specified by dump_level 11, using the vmlinux file, and saving to dumpfile.

```bash
# makedumpfile -d 11 -x vmlinux /proc/vmcore dumpfile
```

--------------------------------

### Rearrange Flattened Dump Data

Source: https://www.linux.org/docs/man8/makedumpfile.html

The -R option rearranges dump data from standard input (flattened format) into a normal DUMPFILE readable by analysis tools. This can be used directly or after receiving data via SSH.

```bash
# makedumpfile -R dumpfile < dumpfile.tmp
```

```bash
# makedumpfile -F -d 31 -x vmlinux /proc/vmcore \
| ssh user@host "makedumpfile -R dumpfile"
```
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