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.
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.