Discussed on hackers and recommended for inclusion into 9.0 at the devsummit.
All support email to devin dteske at vicor dot ignoreme dot com .
Submitted by: dteske at vicor dot ignoreme dot com
Reviewed by: me and many others
functions used in the bootloader. The goal is to make the code more
readable and smaller (especially because we have size issues
in the loader's environment).
High level description of the changes:
+ define some string manipulation functions to improve readability;
+ create functions to manipulate module descriptors, removing some
duplicated code;
+ rename the error codes to ESOMETHING;
+ consistently use set_environment_variable (which evaluates
$variables) when interpreting variable=value assignments;
I have tested the code, but there might be code paths that I have
not traversed so please let me know of any issues.
Details of this change:
--- loader.4th ---
+ add some module operators, to remove duplicated code while parsing
module-related commands:
set-module-flag
enable-module
disable-module
toggle-module
show-module
--- pnp.4th ---
+ move here the definition related to the pnp devices list, e.g.
STAILQ_* , pnpident, pnpinfo
--- support.4th ---
+ rename error codes to capital e.g. ENOMEM EFREE ... and do obvious
changes related to the renaming;
+ remove unused structures (those relevant to pnp are moved to pnp.4th)
+ various string functions
- strlen removed (it is an internal function)
- strchr, defined as the C function
- strtype -- type a string to output
- strref -- assign a reference to the string on the stack
- unquote -- remove quotes from a string
+ remove reset_line_buffer
+ move up the 'set_environment_variable' function (which now
uses the interpreter, so $variables are evaluated).
Use the function in various places
+ add a 'test_file function' for debugging purposes
MFC after: 4 weeks
loader_conf_files="foo bar baz"
should cause loading the files listed, and then resume with the
remaining config files (from previous values of the variable).
Unfortunately, sometimes the line was ignored -- actually even
modifying the line in /boot/default/loader.conf sometimes doesn't work.
ANALYSIS: After much investigation, turned out to be a bug in the logic.
The existing code detected a new assignment by looking at the address
of the the variable containing the string. This only worked by pure
chance, i.e. if the new string is longer than the previous value
then the memory allocator may return a different address
to store the string hence triggering the detection.
SOLUTION: This commit contains a minimal change to fix the problem,
without altering too much the existing structure of the code.
However, as a step towards improving the quality and reliability of
this code, I have introduced a handful of one-line functions
(strget, strset, strfree, string= ) that could be used in dozens
of places in the existing code.
HOWEVER:
There is a much bigger problem here. Even though I am no Forth
expert (as most fellow src committers) I can tell that much of the
forth code (in support.4th at least) is in severe need of a
review/refactoring:
+ pieces of code are replicated multiple times instead of writing
functions (see e.g. set_module_*);
+ a lot of stale code (e.g. "structure" definitions for
preloaded_files, kernel_module, pnp stuff) which is not used
or at least belongs elsewhere.
The code bload is extremely bad as the loader runs with very small
memory constraints, and we already hit the limit once (see
http://svn.freebsd.org/viewvc/base?view=revision&revision=185132
Reducing the footprint of the forth files is critical.
+ two different styles of coding, one using pure stack functions
(maybe beautiful but surely highly unreadable), one using
high level mechanisms to give names to arguments and local
variables (which leads to readable code).
Note that this code is used by default by all FreeBSD installations,
so the fragility and the code bloat are extremely damaging.
I will try to work fixing the three items above, but if others have
time, please have a look at these issues.
MFC after: 4 weeks
this is called /boot/nextboot.conf. This file is required to have it's first
line be nextboot_enable="YES" for it to be read. Also, this file is
rewritten by the loader to nextboot_enable="NO"<space> after it is read.
This makes it so the file is read exactly once. Finally, the nextboot.conf
is removed shortly after the filesystems are mounted r/w.
Caution should be taken as you can shoot yourself in the foot. This is only
the loader piece. There will be a tool called nextboot(8) that will manage
the nextboot.conf file for you. It is coming shortly.
Reviewed by: dcs
Approved by: jake (mentor)
- Change the 'fopen' keyword to accept a mode parameter. Note that this
will break existing 4th scripts that use fopen. Thus, the loader
version has been bumped and loader.4th has been changed to check for a
sufficient version on i386 and alpha. Be sure that you either do a full
world build or install or full build and install of sys/boot after this
since loader.old won't work with the new 4th files and vice versa.
PR: kern/32389
Submitted by: Jonathan Mini <mini@haikugeek.com>
Sponsored by: ClickArray, Inc.
used by start to find the kernel. Fix this.
Also, boot would proceed immediately in the absence of a path as
argument. Check first if a kernel has already been loaded, and, if
not, fall back to load kernel&modules behavior.
Some further factorizing. I deem this code to be mostly readable by
now! :-)
Many thanks to: Makoto MATSUSHITA <matusita@jp.FreeBSD.org>
The boot-conf and boot code had various bugs, and some of it was big,
ugly, unwieldy, and, sometimes, plain incorrect. I'm just about
completely replaced these ugly parts with something much more manageable.
Minor changes were made to the well-factorized parts of it, to accomodate
the new code.
Of note:
* make sure boot-conf has the exact same behavior wrt boot order
as start.
* Correct both boot and boot-conf so they'll work correctly when
compiled in, as they both had some bugs, minor and major.
* Remove all the crud from loader.4th back into support.4th, for
the first time since boot-conf was first improved. Hurray!
I'm fairly satisfied with the code at this time. Time to see about those
man pages...
as the kernel name. The one very unfortunate consequence is that kernel
as an absolute path loses the priority. It will only be tried after
/boot/${kernel}/${bootfile}. I'll see what can be done about it later.
Load the first of the following kernels to be found:
${kernel} if ${kernel} is an absolute path
/boot/${kernel}/${kernel}
/boot/${kernel}/${bootfile}
${kernel}/${kernel}
${kernel}/${bootfile}
${kernel}
${bootfile}
The last instance of ${kernel} and ${bootfile} will be treated as a
list of semicolon separated file names, and each will be tried in turn,
from left to right.
Also, for each filename loader(8) will try filename, filename.ko,
filename.gz, filename.ko.gz, in that order, but that's not related
to this code.
This resulted in a major reorganization of the code, and much of what
was accumulating on loader.4th was rightly transfered to support.4th.
The semantics of boot-conf and boot also changed. Both will try to load
a kernel the same as above.
After a kernel was loaded, the variable module_path may get changed. Such
change will happen if the kernel was found with a directory prefix. In
that case, the module path will be set to ${directory};${module_path}.
Next, the modules are loaded as usual.
This is intended so kernel="xyzzy" in /boot/loader.conf will load
/boot/xyzzy/kernel.ko, load system modules from /boot/xyzzy/, and
load third party modules from /boot/modules or /modules. If that doesn't
work, it's a bug.
Also, fix a breakage of "boot" which was recently introduced. Boot without
any arguments would fail. No longer. Also, boot will only unload/reload
if the first argument is a path. If no argument exists or the first
argument is a flag, boot will use whatever is already loaded. I hope this
is POLA. That behavior is markedly different from that of boot-conf, which
will always unload/reload.
The semantics introduced here are experimental. Even if the code works,
we might decide this is not the prefered behavior. If you feel so, send
your feedback. (Yeah, this belongs in a HEADS UP or something, but I've
been working for the past 16 hours on this stuff, so gimme a break.)
code into a more modular interface, with hidden vocabularies and
such. Remove the need to a lot of ugly initialization.
Also, add a few structure definitions, from stuff used on the C
part of loader. Some of this will disappear, and the crude structure
support will most likely be replaced by full-blown OOP support
already present on FICL, but not installed by default. But it was
getting increasingly inconvenient to keep this separate on my tree,
and I already lost lots of work once because of the hurdles, so
commit this.
Anyway, it makes support.4th more structured, and I'm not proceeding
with the work on it any time soon, unfortunately.
