imgact_elf: Add const to the checknote parameter to __elfN(parse_notes)

Reviewed by: imp, kib
Sponsored by: University of Cambridge, Google, Inc.
Differential Revision: https://reviews.freebsd.org/D44215

imgact_elf: Add const to a few struct image_params pointers

This makes it more obvious which functions modify fields in this struct.

Reviewed by: imp, kib
Obtained from: CheriBSD
Differential Revision: https://reviews.freebsd.org/D44214

imgact_elf: Add const to the header_supported callback arguments

This callback shouldn't be modifying any of the arguments.

Reviewed by: imp, kib, emaste, jhb
Obtained from: CheriBSD
Differential Revision: https://reviews.freebsd.org/D44193

imgact_elf: Export __elfN(parse_notes)

This is useful to check if a note is present and contains an expected
value, e.g. to read NT_GNU_PROPERTY_TYPE_0 on arm64 to see if we should
enable BTI.

Reviewed by: kib, markj
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D42439

imgact_elf: Move GNU_ABI_VENDOR to a common header

Move the definition of GNU_ABI_VENDOR to a common location so it can
be used in multiple files.

Reviewed by: emaste, kib, imp
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D42442

sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

Brandinfo: Retire emul_path as unneeded anymore

The Barndinfo emul_path was used by the Elf image activator to fixup
interpreter file name according to ABI root directory. Since the
non-native ABI can now specify its root directory directly to namei()
via pwd_altroot() call this facility is not needed anymore.

Differential Revision: https://reviews.freebsd.org/D40091
MFC after: 2 month

imgact_elf: Change header_supported to return bool instead of boolean_t.

Reviewed by: imp, kib, emaste
Differential Revision: https://reviews.freebsd.org/D39919

exec: Remove the stack gap implementation

ASLR stack randomization will reappear in a forthcoming commit. Rather
than inserting a random gap into the stack mapping, the entire stack
mapping itself will be randomized in the same way that other mappings
are when ASLR is enabled.

No functional change intended, as the stack gap implementation is
currently disabled by default.

Reviewed by: kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33704

elf*_brand_inuse: Change return type to bool.

Reviewed by: kib
Obtained from: CheriBSD
Sponsored by: The University of Cambridge, Google Inc.
Differential Revision: https://reviews.freebsd.org/D33052

setrlimit: Take stack gap into account.

Calling setrlimit with stack gap enabled and with low values of stack
resource limit often caused the program to abort immediately after
exiting the syscall. This happened due to the fact that the resource
limit was calculated assuming that the stack started at sv_usrstack,
while with stack gap enabled the stack is moved by a random number
of bytes.

Save information about stack size in struct vmspace and adjust the
rlim_cur value. If the rlim_cur and stack gap is bigger than rlim_max,
then the value is truncated to rlim_max.

PR: 253208
Reviewed by: kib
Obtained from: Semihalf
Sponsored by: Stormshield
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D31516

Add a link to the Elf_Brandinfo into the struc proc.

To allow the ABI to make a dicision based on the Brandinfo add a link
to the Elf_Brandinfo into the struct proc. Add a note that the high 8 bits
of Elf_Brandinfo flags is private to the ABI.

Note to MFC: it breaks KBI.

Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D30918
MFC after: 2 weeks

Add infrastructure required for Linux coredump support

This adds `sv_elf_core_osabi`, `sv_elf_core_abi_vendor`,
and `sv_elf_core_prepare_notes` fields to `struct sysentvec`,
and modifies imgact_elf.c to make use of them instead
of hardcoding FreeBSD-specific values. It also updates all
of the ABI definitions to preserve current behaviour.

This makes it possible to implement non-native ELF coredump
support without unnecessary code duplication. It will be used
for Linux coredumps.

Reviewed By: kib
Sponsored By: EPSRC
Differential Revision: https://reviews.freebsd.org/D30921

Unstaticize parts of coredumping code

This makes it possible to call __elfN(size_segments) and __elfN(puthdr)
from Linux coredump code.

Reviewed By: kib
Sponsored By: EPSRC
Differential Revision: https://reviews.freebsd.org/D30455

Pass pointers to info parsed from notes, to brandinfo->header_supported filter.

Currently, we parse notes for the values of ELF FreeBSD feature flags
and osrel. Knowing these values, or knowing that image does not carry
the note if pointers are NULL, is useful to decide which ABI variant
(brand) we want to activate for the image.

Right now this is only a plumbing change

Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D25273

Introduce an AUXARGS_ENTRY_PTR() macro.

As the name implys, it uses the a_ptr member of the auxarg entry (except
in compat32 where it uses a_val). This is more correct and required for
systems where a_val is not the same size or hardware type as a_ptr (e.g.
CHERI).

This is a prepratory commit for D24407.

Reviewed by: kib
Obtained from: CheriBSD
Sponsored by: DARPA

Copy out aux args after the argument and environment vectors.

Partially revert r354741 and r354754 and go back to allocating a
fixed-size chunk of stack space for the auxiliary vector. Keep
sv_copyout_auxargs but change it to accept the address at the end of
the environment vector as an input stack address and no longer
allocate room on the stack. It is now called at the end of
copyout_strings after the argv and environment vectors have been
copied out.

This should fix a regression in r354754 that broke the stack alignment
for newer Linux amd64 binaries (and probably broke Linux arm64 as
well).

Reviewed by: kib
Tested on: amd64 (native, linux64 (only linux-base-c7), and i386)
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D22695

Use uintptr_t instead of register_t * for the stack base.

- Use ustringp for the location of the argv and environment strings
and allow destp to travel further down the stack for the stackgap
and auxv regions.
- Update the Linux copyout_strings variants to move destp down the
stack as was done for the native ABIs in r263349.
- Stop allocating a space for a stack gap in the Linux ABIs. This
used to hold translated system call arguments, but hasn't been used
since r159992.

Reviewed by: kib
Tested on: md64 (amd64, i386, linux64), i386 (i386, linux)
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D22501

Check for errors from copyout() and suword*() in sv_copyout_args/strings.

Reviewed by: brooks, kib
Tested on: amd64 (amd64, i386, linux64), i386 (i386, linux)
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D22401

Add a sv_copyout_auxargs() hook in sysentvec.

Change the FreeBSD ELF ABIs to use this new hook to copyout ELF auxv
instead of doing it in the sv_fixup hook. In particular, this new
hook allows the stack space to be allocated at the same time the auxv
values are copied out to userland. This allows us to avoid wasting
space for unused auxv entries as well as not having to recalculate
where the auxv vector is by walking back up over the argv and
environment vectors.

Reviewed by: brooks, emaste
Tested on: amd64 (amd64 and i386 binaries), i386, mips, mips64
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D22355

Make randomized stack gap between strings and pointers to argv/envs.

This effectively makes the stack base on the csu _start entry
randomized.

The gap is enabled if ASLR is for the ABI is enabled, and then
kern.elf{64,32}.aslr.stack_gap specify the max percentage of the
initial stack size that can be wasted for gap. Setting it to zero
disables the gap, and max is capped at 50%.

Only amd64 for now.

Reviewed by: cem, markj
Discussed with: emaste
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D21081

Avoid two suword() calls per auxarg entry.

Instead, construct an auxargs array and copy it out all at once.

Use an array of Elf_Auxinfo rather than pairs of Elf_Addr * to represent
the array. This is the correct type where pairs of words just happend
to work. To reduce the size of the diff, AUXARGS_ENTRY is altered to act
on this array rather than introducing a new macro.

Return errors on copyout() and suword() failures and handle them in the
caller.

Incidentally fixes AT_RANDOM and AT_EXECFN in 32-bit linux on amd64
which incorrectly used AUXARG_ENTRY instead of AUXARGS_ENTRY_32
(now removed due to the use of proper types).

Reviewed by: kib
Comments from: emaste, jhb
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D15485

Use C99 boolean type for translate_osrel

Migrate to modern types before creating MD Linuxolator bits for new
architectures.

Reviewed by: cem
Sponsored by: Turing Robotic Industries Inc.
Differential Revision: https://reviews.freebsd.org/D14676

sys/sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Update r315753 with the proper flag name.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Add a flag BI_BRAND_ONLY_STATIC to specify that the brand only
matches static binaries.

Interpretation of the 'static' there is that the binary must not
specify an interpreter. In particular, shared objects are matched by
the brand if BI_CAN_EXEC_DYN is also set.

This improves precision of the brand matching, which should eliminate
surprises due to brand ordering.

Revert r315701.

Discussed with and tested by: ed (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Add forward declaration for struct vnode.

The coredump() function provided by this header file has struct vnode *
as an argument.

MFC after: 1 week

sys/sys: minor spelling fixes.

While the changes are minor, these headers are very visible.

MFC after: 2 weeks

Add missing forward declaration of struct image_params.

Export the eflags field from the elf header. This allows better
discrimination between different subarch binaries, at least for mips
and arm. Arm is implemented, mips is still tbd, so not currently
exported. aarch64 does not export this because aarch64 binaries use
different tags and flags than arm.

Differential Revision: https://reviews.freebsd.org/D2611

Improve support for XSAVE with debuggers.
- Dump an NT_X86_XSTATE note if XSAVE is in use. This note is designed
to match what Linux does in that 1) it dumps the entire XSAVE area
including the fxsave state, and 2) it stashes a copy of the current
xsave mask in the unused padding between the fxsave state and the
xstate header at the same location used by Linux.
- Teach readelf() to recognize NT_X86_XSTATE notes.
- Change PT_GET/SETXSTATE to take the entire XSAVE state instead of
only the extra portion. This avoids having to always make two
ptrace() calls to get or set the full XSAVE state.
- Add a PT_GET_XSTATE_INFO which returns the length of the current
XSTATE save area (so the size of the buffer needed for PT_GETXSTATE)
and the current XSAVE mask (%xcr0).

Differential Revision: https://reviews.freebsd.org/D1193
Reviewed by: kib
MFC after: 2 weeks

Expand the elf brandelf infrastructure to give access to the whole ELF
header (Elf_Ehdr) to determine if a particular interpretor wants to
accept it or not. Use this mechanism to filter EABI arm on OABI arm
kernels, and vice versa. This method could also be used to implement
OABI on EABI arm kernels, if desired, or to allow a single mips kernel
to run o32, n32 and n64 binaries.

Differential Revision: https://reviews.freebsd.org/D609

Revert r266925 as it can lead to instant panic at fexecve():

To allow to run the interpreter itself add a new ELF branding type.

Pointed out by: kib, mjg

To allow to run the interpreter itself add a new ELF branding type.
Allow Linux ABI to run ELF interpreter.

MFC after: 3 days

Convert files to UTF-8

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Reword the comment, fixing typo.

MFC after: 3 days

Merge projects/enhanced_coredumps (r204346) into HEAD:

Enhanced process coredump routines.

This brings in the following features:
1) Limit number of cores per process via the %I coredump formatter.
Example:
if corefilename is set to %N.%I.core AND num_cores = 3, then
if a process "rpd" cores, then the corefile will be named
"rpd.0.core", however if it cores again, then the kernel will
generate "rpd.1.core" until we hit the limit of "num_cores".

this is useful to get several corefiles, but also prevent filling
the machine with corefiles.

2) Encode machine hostname in core dump name via %H.

3) Compress coredumps, useful for embedded platforms with limited space.
A sysctl kern.compress_user_cores is made available if turned on.

To enable compressed coredumps, the following config options need to be set:
options COMPRESS_USER_CORES
device zlib # brings in the zlib requirements.
device gzio # brings in the kernel vnode gzip output module.

4) Eventhandlers are fired to indicate coredumps in progress.

5) The imgact sv_coredump routine has grown a flag to pass in more
state, currently this is used only for passing a flag down to compress
the coredump or not.

Note that the gzio facility can be used for generic output of gzip'd
streams via vnodes.

Obtained from: Juniper Networks
Reviewed by: kan

MFC r196653:
Make sure FreeBSD binaries without .note.ABI-tag section work
correctly and do not match a colliding Debian GNU/kFreeBSD
brandinfo statements.
For this mark the Debian GNU/kFreeBSD brandinfo that it must have
an .note.ABI-tag section and ignore the old EI_OSABI brandinfo
when comparing a possibly colliding set of options.

Due to SYSINIT we add the brandinfo in a non-deterministic order,
so native FreeBSD is not always first. We may want to consider
to force native FreeBSD to come first as well.

The only way a problem could currently be noticed is when running an
i386 binary without the .note.ABI-tag on amd64 and the Debian GNU/kFreeBSD
brandinfo was matched first, as the fallback to ld-elf32.so.1 does
not exist in that case.

Reported and tested by: ticso
In collaboration with: kib
MFC after: 3 days
Approved by: re (rwatson)

Make sure FreeBSD binaries without .note.ABI-tag section work
correctly and do not match a colliding Debian GNU/kFreeBSD
brandinfo statements.
For this mark the Debian GNU/kFreeBSD brandinfo that it must have
an .note.ABI-tag section and ignore the old EI_OSABI brandinfo
when comparing a possibly colliding set of options.

Due to SYSINIT we add the brandinfo in a non-deterministic order,
so native FreeBSD is not always first. We may want to consider
to force native FreeBSD to come first as well.

The only way a problem could currently be noticed is when running an
i386 binary without the .note.ABI-tag on amd64 and the Debian GNU/kFreeBSD
brandinfo was matched first, as the fallback to ld-elf32.so.1 does
not exist in that case.

Reported and tested by: ticso
In collaboration with: kib
MFC after: 3 days

MFC r196512:

Fix handling of .note.ABI-tag section for GNU systems [1].
Handle GNU/Linux according to LSB Core Specification 4.0,
Chapter 11. Object Format, 11.8. ABI note tag.

Also check the first word of desc, not only name, according to
glibc abi-tags specification to distinguish between Linux and
kFreeBSD.

Add explicit handling for Debian GNU/kFreeBSD, which runs
on our kernels as well [2].

In {amd64,i386}/trap.c, when checking osrel of the current process,
also check the ABI to not change the signal behaviour for Linux
binary processes, now that we save an osrel version for all three
from the lists above in struct proc [2].

These changes make it possible to run FreeBSD, Debian GNU/kFreeBSD
and Linux binaries on the same machine again for at least i386 and
amd64, and no longer break kFreeBSD which was detected as GNU(/Linux).

PR: kern/135468
Submitted by: dchagin [1] (initial patch)
Suggested by: kib [2]
Tested by: Petr Salinger (Petr.Salinger seznam.cz) for kFreeBSD
Reviewed by: kib
Approved by: re (kensmith)

Fix handling of .note.ABI-tag section for GNU systems [1].
Handle GNU/Linux according to LSB Core Specification 4.0,
Chapter 11. Object Format, 11.8. ABI note tag.

Also check the first word of desc, not only name, according to
glibc abi-tags specification to distinguish between Linux and
kFreeBSD.

Add explicit handling for Debian GNU/kFreeBSD, which runs
on our kernels as well [2].

In {amd64,i386}/trap.c, when checking osrel of the current process,
also check the ABI to not change the signal behaviour for Linux
binary processes, now that we save an osrel version for all three
from the lists above in struct proc [2].

These changes make it possible to run FreeBSD, Debian GNU/kFreeBSD
and Linux binaries on the same machine again for at least i386 and
amd64, and no longer break kFreeBSD which was detected as GNU(/Linux).

PR: kern/135468
Submitted by: dchagin [1] (initial patch)
Suggested by: kib [2]
Tested by: Petr Salinger (Petr.Salinger seznam.cz) for kFreeBSD
Reviewed by: kib
MFC after: 3 days

Fix KBI breakage by r190520 which affects older linux.ko binaries:

1) Move the new field (brand_note) to the end of the Brandinfo structure.
2) Add a new flag BI_BRAND_NOTE that indicates that the brand_note pointer
is valid.
3) Use the brand_note field if the flag BI_BRAND_NOTE is set and as old
modules won't have the flag set, so the new field brand_note would be
ignored.

Suggested by: jhb
Reviewed by: jhb
Approved by: kib (mentor)
MFC after: 6 days

Implement new way of branding ELF binaries by looking to a
".note.ABI-tag" section.

The search order of a brand is changed, now first of all the
".note.ABI-tag" is looked through.

Move code which fetch osreldate for ELF binary to check_note() handler.

PR: 118473
Approved by: kib (mentor)

Back out a non-style(9) change from r186668 to unbreak the kernels.

style(9)
Differences from 'svn diff -x -Bbw' are trivially verifiable as only style(9).

Remove sysctl debug.elf_trace and the trace field in auxargs. They go
nowhere. It used to be the equivalent of $LD_DEBUG in rtld-elf.
Elf_Auxargs is an internal structure.

- Import the HEAD csup code which is the basis for the cvsmode work.

Remove kern.elf32.can_exec_dyn sysctl. Instead extend Brandinfo structure
with flags bitfield and set BI_CAN_EXEC_DYN flag for all brands that usually
allow executing elf dynamic binaries (aka shared libraries). When it is
requested to execute ET_DYN elf image check if this flag is on after we
know the elf brand allowing execution if so.

PR: kern/87615
Submitted by: Marcin Koziej <creep@desk.pl>

Make our ELF64 type definitions match standards. In particular this
means:
o Remove Elf64_Quarter,
o Redefine Elf64_Half to be 16-bit,
o Redefine Elf64_Word to be 32-bit,
o Add Elf64_Xword and Elf64_Sxword for 64-bit entities,
o Use Elf_Size in MI code to abstract the difference between
Elf32_Word and Elf64_Word.
o Add Elf_Ssize as the signed counterpart of Elf_Size.

MFC after: 2 weeks

Add __elfN(dump_thread). This function is called from __elfN(coredump)
to allow dumping per-thread machine specific notes. On ia64 we use this
function to flush the dirty registers onto the backingstore before we
write out the PRSTATUS notes.

Tested on: alpha, amd64, i386, ia64 & sparc64
Not tested on: arm, powerpc

Add an additional field to the elf brandinfo structure to support
quicker exec-time replacement of the elf interpreter on an emulation
environment where an entire /compat/* tree isn't really warranted.

- Provide backwards compatibility for kern.fallback_elf_brand.
- Use the generic elf type macros in imgact_elf.h instead of ifdefing the
entire contents of the header.

Infrastructure tweaks to allow having both an Elf32 and an Elf64 executable
handler in the kernel at the same time. Also, allow for the
exec_new_vmspace() code to build a different sized vmspace depending on
the executable environment. This is a big help for execing i386 binaries
on ia64. The ELF exec code grows the ability to map partial pages when
there is a page size difference, eg: emulating 4K pages on 8K or 16K
hardware pages.

Flesh out the i386 emulation support for ia64. At this point, the only
binary that I know of that fails is cvsup, because the cvsup runtime
tries to execute code in pages not marked executable.

Obtained from: dfr (mostly, many tweaks from me).

Fix typo in the BSD copyright: s/withough/without/

Spotted and suggested by: des
MFC after: 3 weeks

Remove __P

KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after: ha ha ha ha

MFS: bring the consistent `compat_3_brand' support into -CURRENT
(the work was first done in the RELENG_4 branch near a release
during a MFC to make the code cleaner and more consistent)

Change Elf64_Brandinfo::brand from char* to int.

Change our ELF binary branding to something more acceptable to the Binutils
maintainers.

After we established our branding method of writing upto 8 characters of
the OS name into the ELF header in the padding; the Binutils maintainers
and/or SCO (as USL) decided that instead the ELF header should grow two new
fields -- EI_OSABI and EI_ABIVERSION. Each of these are an 8-bit unsigned
integer. SCO has assigned official values for the EI_OSABI field. In
addition to this, the Binutils maintainers and NetBSD decided that a better
ELF branding method was to include ABI information in a ".note" ELF
section.

With this set of changes, we will now create ELF binaries branded using
both "official" methods. Due to the complexity of adding a section to a
binary, binaries branded with ``brandelf'' will only brand using the
EI_OSABI method. Also due to the complexity of pulling a section out of an
ELF file vs. poking around in the ELF header, our image activator only
looks at the EI_OSABI header field.

Note that a new kernel can still properly load old binaries except for
Linux static binaries branded in our old method.

*
* For a short period of time, ``ld'' will also brand ELF binaries
* using our old method. This is so people can still use kernel.old
* with a new world. This support will be removed before 5.0-RELEASE,
* and may not last anywhere upto the actual release. My expiration
* time for this is about 6mo.
*

Change #ifdef KERNEL to #ifdef _KERNEL in the public headers. "KERNEL"
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot). This is consistant with the other
BSD's who made this change quite some time ago. More commits to come.

General cleanup of core-dumping code.

Submitted by: Sean Fagan,

$Id$ -> $FreeBSD$

Hmm- I must be blind. There *was* already an appropriate typedef still
left there. The typedef that was inserted negated the correct typedef.
This may have just been cvs automerge foo. Sorry.

I don't know what happened here- I submitted a *working* patch for
alpha to John Polstra yesterday and it was checked in. Then there
was a bunch of CVS activity, and it ended up with the *broken*
prototype being reinserted. All I see in the history is 'style nits'
as a comment, and I certainly agree with the latter of those two words.

Style nit: sort elf_brand_inuse() prototype in with the others.
Prototype also needed to be added for !ELFCLASS32 case.

Submitted by: bde

Provide elf_brand_inuse() as a method an emulator can use to find out
whether it is currently in use (which is kinda useful when it's about
to unload itself: Lockups are never very much fun, are they?).

Don't use __BEGIN_DECLS/__END_DECLS in the kernel.

Fixed some other, even more minor style bugs.

Add provisions for variant core dump file formats, depending on the
object format of the executable being dumped. This is the first
step toward producing ELF core dumps in the proper format. I will
commit the code to generate the ELF core dumps Real Soon Now. In
the meantime, ELF executables won't dump core at all. That is
probably no less useful than dumping a.out-style core dumps as they
have done until now.

Submitted by: Alex <garbanzo@hooked.net> (with very minor changes by me)

Use Elf_Addr to store addresses instead of Elf_Word.

This commit fixes various 64bit portability problems required for
FreeBSD/alpha. The most significant item is to change the command
argument to ioctl functions from int to u_long. This change brings us
inline with various other BSD versions. Driver writers may like to
use (__FreeBSD_version == 300003) to detect this change.

The prototype FreeBSD/alpha machdep will follow in a couple of days
time.

Some staticized variables were still declared to be extern.

Fill out the ELF header files to make them more or less complete.
Fix a macro name that was misspelled both in brandelf.c and
imgact_elf.h.

Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

Prepare kernel to take advantage of "branded" ELF binaries.

First attempt at FreeBSD & Linux ELF support.

Compile and link a new kernel, that will give native ELF support, and
provide the hooks for other ELF interpreters as well.

To make native ELF binaries use John Polstras elf-kit-1.0.1..
For the time being also use his ld-elf.so.1 and put it in
/usr/libexec.

The Linux emulator has been enhanced to also run ELF binaries, it
is however in its very first incarnation.
Just get some Linux ELF libs (Slackware-3.0) and put them in the
prober place (/compat/linux/...).
I've ben able to run all the Slackware-3.0 binaries I've tried
so far.
(No it won't run quake yet :)