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ksplice-create

NAME

ksplice-create - Create a set of kernel modules for a rebootless kernel update

SYNOPSIS

ksplice-create [--config=ORIG_CONFIG] --patch=PATCH_FILE KERNEL_SOURCE

ksplice-create [--config=ORIG_CONFIG] --diffext=EXTENSION KERNEL_SOURCE

ksplice-create [--config=ORIG_CONFIG] --prebuild KERNEL_SOURCE

DESCRIPTION

ksplice-create creates a set of Ksplice kernel modules that, when loaded, will apply a user-specified source code patch to the running binary kernel.

Before you use ksplice-create on a patch, you should confirm that the desired source code change does not make any semantic changes to kernel data structures---that is, changes that would require existing instances of kernel data structures to be transformed (e.g., a patch that adds a field to a global data structure would require the existing data structures to change). If you use Ksplice on a patch that changes data structure semantics, Ksplice will not detect the problem and you could experience kernel problems as a result.

The to-be-applied source code patch can be specified by providing a patch(1) file (--patch=PATCH_FILE) or by providing a file extension (--diffext=EXTENSION).

If a file extension is specified, then the desired source code patch will be determined by comparing all of the files in the KERNEL_SOURCE directory tree whose names end with the extra extension EXTENSION against the corresponding files without the extra extension. Only the new files containing the extra extension in their filenames should be modified.

Here is an example of using a file extension to specify a patch:

  $ cp KERNEL_SOURCE/kernel/sys.c KERNEL_SOURCE/kernel/sys.c.prctl_fixed
  [edit sys.c.prctl_fixed to include the desired changes]
  $ ksplice-create --diffext=.prctl_fixed KERNEL_SOURCE
 
 

KERNEL_SOURCE must be a directory containing the to-be-updated kernel's original source code. If your Linux distribution applies patches to the Linux kernel during the kernel build process, then those patches must be applied to the KERNEL_SOURCE directory before invoking ksplice-create on that directory. ksplice-create will not modify the source code in the KERNEL_SOURCE directory tree, but it will perform a kernel build in that directory tree.

ORIG_CONFIG can be used to specify the directory containing the to-be-updated kernel's original .config file and original System.map file (the files should have exactly those names). ORIG_CONFIG defaults to KERNEL_SOURCE/ksplice.

The default gcc(1) compiler and as(1) assembler on the system should be as close to the compiler and assembler originally used to build the running kernel as possible. If the current compiler and linker are too different from the original compiler and linker, ksplice-apply will abort when applying the update.

ksplice-create outputs a tar(1) file, compressed with gzip(1), containing the desired Ksplice update modules. This tarball will be created in the current directory, and it can be manipulated using the other Ksplice utilities, such as ksplice-apply.

The first time that ksplice-create is invoked on a KERNEL_SOURCE directory, it must build that kernel from scratch, which is much slower than the rest of the update-creation process. --prebuild can be used to perform this initial kernel build without providing a source code patch.

In order to patch a function that has previously been patched by Ksplice, the user needs to ensure that the KERNEL_SOURCE directory provided to Ksplice contains the source for the currently running kernel, including any patches that have previously been applied by Ksplice.

OPTIONS

-v, --verbose

Causes ksplice-create to print debugging messages about its progress. Using multiple -v options increases the verbosity. The maximum is 2.

-j JOBS, --jobs=JOBS

Specifies the number of jobs to run simultaneously while performing kernel builds. ksplice-create also honors the environment variable CONCURRENCY_LEVEL.

--patch-opt=OPTIONS

Can be used to pass options to patch(1). If this option is NOT specified, then -p1 is passed to patch. If this option is specified, then only the specified options will be passed to patch. This option can be repeated in order to pass multiple options to patch. This option is ignored when the to-be-applied source code patch is specified using --diffext.

--id=ID

Specifies the unique value that will be used as the identifier of the Ksplice update. This identifier will, for example, appear in the name of the update tarball. By default, a random 8-character ID will be generated.

SEE ALSO

ksplice-apply(8), ksplice-view(8), ksplice-undo(8)

BUGS

Please report bugs to <devel@ksplice.com>.

COPYRIGHT

Copyright (C) 2007-2008 Jeff Arnold <jbarnold@mit.edu>

Copyright (C) 2008 Anders Kaseorg <andersk@mit.edu>,
                    Tim Abbott <tabbott@mit.edu>

This is free software and documentation. You can redistribute and/or modify it under the terms of the GNU General Public License, version 2.