freebsd-skq/rescue
jhb ab35544b83 Add support to libkvm for reading vmcores from other architectures.
- Add a kvaddr_type to represent kernel virtual addresses instead of
  unsigned long.
- Add a struct kvm_nlist which is a stripped down version of struct nlist
  that uses kvaddr_t for n_value.
- Add a kvm_native() routine that returns true if an open kvm descriptor
  is for a native kernel and memory image.
- Add a kvm_open2() function similar to kvm_openfiles().  It drops the
  unused 'swapfile' argument and adds a new function pointer argument for
  a symbol resolving function.  Native kernels still use _fdnlist() from
  libc to resolve symbols if a resolver function is not supplied, but cross
  kernels require a resolver.
- Add a kvm_nlist2() function similar to kvm_nlist() except that it uses
  struct kvm_nlist instead of struct nlist.
- Add a kvm_read2() function similar to kvm_read() except that it uses
  kvaddr_t instead of unsigned long for the kernel virtual address.
- Add a new kvm_arch switch of routines needed by a vmcore backend.
  Each backend is responsible for implementing kvm_read2() for a given
  vmcore format.
- Use libelf to read headers from ELF kernels and cores (except for
  powerpc cores).
- Add internal helper routines for the common page offset hash table used
  by the minidump backends.
- Port all of the existing kvm backends to implement a kvm_arch switch and
  to be cross-friendly by using private constants instead of ones that
  vary by platform (e.g. PAGE_SIZE).  Static assertions are present when
  a given backend is compiled natively to ensure the private constants
  match the real ones.
- Enable all of the existing vmcore backends on all platforms.  This means
  that libkvm on any platform should be able to perform KVA translation
  and read data from a vmcore of any platform.

Tested on:	amd64, i386, sparc64 (marius)
Differential Revision:	https://reviews.freebsd.org/D3341
2015-11-27 18:58:26 +00:00
..
librescue META_MODE: Remove DEP_MACHINE from Makefile.depend files. 2015-09-25 19:44:01 +00:00
rescue Add support to libkvm for reading vmcores from other architectures. 2015-11-27 18:58:26 +00:00
Makefile
README

The /rescue build system here has three goals:

1) Produce a reliable standalone set of /rescue tools.

The contents of /rescue are all statically linked and do not depend on
anything in /bin or /sbin.  In particular, they'll continue to
function even if you've hosed your dynamic /bin and /sbin.  For
example, note that /rescue/mount runs /rescue/mount_nfs and not
/sbin/mount_nfs.  This is more subtle than it looks.

As an added bonus, /rescue is fairly small (thanks to crunchgen) and
includes a number of tools (such as gzip, bzip2, vi) that are not
normally found in /bin and /sbin.

2) Demonstrate robust use of crunchgen.

These Makefiles recompile each of the crunchgen components and include
support for overriding specific library entries.  Such techniques
should be useful elsewhere.  For example, boot floppies could use this
to conditionally compile out features to reduce executable size.

3) Produce a toolkit suitable for small distributions.

Install /rescue on a CD or CompactFlash disk, and symlink /bin and
/sbin to /rescue to produce a small and fairly complete FreeBSD
system.

These tools have one big disadvantage: being statically linked, they
cannot use some advanced library functions that rely on dynamic
linking.  In particular, nsswitch, locales, and pam are likely to all
rely on dynamic linking in the near future.


To compile:

# cd /usr/src/rescue
# make obj
# make
# make install

Note that rebuilds don't always work correctly; if you run into
trouble, try 'make clean' before recompiling.

$FreeBSD$