KSYMS(4) OpenBSD Programmer's Manual KSYMS(4)NAMEksyms - kernel symbol table device
SYNOPSIS
pseudo-device ksyms [count]
DESCRIPTION
The /dev/ksyms device masquerades as an OpenBSD native executable (a.out
or ELF, depending on the platform) with the symbols from the running
kernel as its symbol segment. Use of /dev/ksyms requires that the boot
loader preserve the kernel symbols and place them at the end of the
kernel's address space.
The /dev/ksyms device is used to look up the symbol table name list from
the running kernel. Because it represents the running kernel it is
guaranteed to always be up to date even if the kernel file has been
changed (or is even non-existent). It is most useful when used in
conjunction with nlist(3) or the kvm(3) routines (note that kvm_open(3)
and kvm_openfiles(3) will try /dev/ksyms automatically if the first
parameter to them is the NULL pointer).
FILES
/dev/ksyms
ERRORS
An open of /dev/ksyms will fail if:
[EPERM] An open was attempted with write permissions.
[ENXIO] No kernel symbols were saved by the boot loader (usually
because they were removed with strip(1)), or the kernel has
been compiled without a ``pseudo-device ksyms'' line.
SEE ALSOkvm(3), nlist(3)HISTORY
The /dev/ksyms device appeared in OpenBSD 2.4.
BUGS
It is not possible to mmap(2) /dev/ksyms because the boot loader does not
load the symbol table onto a page boundary (so it is not page aligned).
If all the boot loaders were fixed, mmap(2) support would be trivial.
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9
