Commit Graph

766 Commits

Author SHA1 Message Date
Ruslan Ermilov
f53fadafee Prepare for mdoc(7)NG. 2000-12-27 16:37:32 +00:00
KATO Takenori
dfec8c70fa Disabled boot2 for the moment, because it needs aout tools. 2000-12-24 14:54:34 +00:00
Robert Nordier
1165e4c9a4 Fix column alignment (whitespace-only change). 2000-12-19 00:17:36 +00:00
KATO Takenori
db53335483 Merged from sys/boot/i386/loader/Makefile revision 1.49. 2000-12-16 03:15:48 +00:00
Ruslan Ermilov
c5f49c2585 mdoc(7) police: removed duplicate .Os call. 2000-12-14 12:48:07 +00:00
Robert Nordier
81578f4a33 Strip the .comment and .note sections when stripping. There's no
point in retaining this info, particularly under BTX.
2000-12-13 17:10:38 +00:00
Robert Nordier
1ec5afb81e Add a magic number, for easier identification of boot0. At present,
this is used only by libdisk.
2000-12-12 17:27:35 +00:00
Marcel Moolenaar
d5b14b2a37 Add "empty" makefile. Cross-building fails without it. 2000-12-08 04:08:09 +00:00
Andrey A. Chernov
fea0a15961 Cosmetique: don't use localized date 2000-12-01 01:58:48 +00:00
John Baldwin
0a7f15c202 Set the proper bit in the howto flags for a serial console rather than
setting the index of the bit.  (0xc vs. 0x1000)
2000-11-30 18:33:59 +00:00
Paul Saab
43ab35c8c7 Add support for probing the keyboard from pxeboot which will behave
exactly the same as passing -P to boot2.

Submitted by:	jhb
2000-11-30 14:55:10 +00:00
David E. O'Brien
4a93f235c1 `cdboot' is broken as it cannot load a kernel.
The release engineer keeps using the wrong /boot/cdboot when creating the
ISO images.  So we'll add the 4.0-RELEASE cdboot to the tree until someone
bothers to fix the source so a working `cdboot' is built.
2000-11-27 02:15:13 +00:00
Ruslan Ermilov
f4d874a1db mdoc(7) police: do not split author names in the AUTHORS section. 2000-11-22 09:35:58 +00:00
Ruslan Ermilov
d5874785b9 mdoc(7) police: use the new features of the Nm macro. 2000-11-20 17:05:46 +00:00
Ruslan Ermilov
251c176f41 mdoc(7) police: use certified section headers wherever possible. 2000-11-17 11:44:16 +00:00
Mike Smith
1d6dc22916 The default kernel filename is "kernel" again, not "kernel.ko".
Submitted by:	mckusick
2000-11-17 04:43:56 +00:00
Ben Smithurst
c6662b8e3d remove period from SEE ALSO. 2000-11-15 17:02:54 +00:00
David E. O'Brien
f9c70d7647 Don't use the Gawkism strftime(). Pass in the date stamp on the awk
command line instead.

Approved by:	dcs
2000-11-14 21:02:49 +00:00
Ruslan Ermilov
b5c508fba3 Use Fx macro wherever possible. 2000-11-14 11:20:58 +00:00
Matt Jacob
492ecc5fbd init booted_kernel from environment kernelname (if there) 2000-11-14 08:11:03 +00:00
Matt Jacob
178e6e0fed move init of booted_kernel to bootinfo.c 2000-11-14 08:10:15 +00:00
Benno Rice
4cc1860f9b OpenFirmware/PowerPC loader, part 2.
As of this patchset, the loader builds (under NetBSD/macppc), boots, interacts
and talks to BOOTP/NFS servers.

(main.c was moved from boot/ofw/libofw to boot/ofw/common but has no revision
 history)

Reviewed by:	obrien
2000-11-10 06:39:58 +00:00
Benno Rice
f1fb6c2132 Give the network device a print method.
Reviewed by:	obrien
2000-11-10 06:37:43 +00:00
Benno Rice
5b98b64392 OpenFirmware/PowerPC loader, part 2.
This brings the loader up to the point where I can compile it under
NetBSD/macppc and have it boot, interact and talk to NFS servers.

sys/boot/ofw/libofw/main.c has been deleted (it has no revision history) and
replaced with sys/boot/ofw/common/main.c

Reviewed by:	obrien
2000-11-10 06:29:42 +00:00
Paul Saab
3d122d8e2c Honor the ip address given in the root-path dhcp option.
PR:	21743
Submitted by:	Brian Candler <B.Candler@pobox.com>
2000-11-05 14:55:09 +00:00
Yoshihiro Takahashi
64ee4b5b08 Merged from the following changes.
sys/boot/i386/btx/btx/Makefile		1.9
sys/boot/i386/btx/btx/btx.s		1.23
sys/boot/i386/libi386/biosdisk.c	1.32 and 1.33
sys/boot/i386/libi386/biosmem.c		1.5
sys/boot/i386/libi386/comconsole.c	1.8
sys/boot/i386/libi386/gatea20.c		1.3
sys/boot/i386/libi386/time.c		1.4
sys/boot/i386/libi386/vidconsole.c	1.13
sys/boot/i386/loader/Makefile		1.48
sys/boot/i386/loader/main.c		1.22
2000-11-05 12:35:41 +00:00
Robert Nordier
9e3377b8b3 Support a.out: avoid (%dx) in in/out instructions, and use an m4
macro to supply underscores for externals.
2000-11-04 13:03:52 +00:00
Paul Saab
9193b12844 MF4: Add LOADER_TFTP_SUPPORT make.conf flag. 2000-11-04 08:43:13 +00:00
John Baldwin
f251e6cfa1 The Number of Fixed Disks at memory location 0x475 is only 1 byte, not a
2 byte word.  This fixes machines that probe 30-odd hard drives during boot
in the loader.

Submitted by:	Helpful folks at Tyan via ps
2000-11-02 23:28:12 +00:00
Matthew Hunt
26b5d23688 "it's" --> "its" (possessive).
Correct a malformed sentence.
2000-11-01 00:36:12 +00:00
Nick Hibma
25c8418620 Add entry for umodem 2000-10-30 10:55:03 +00:00
Doug Rabson
445516e4e0 Backout revision 1.7 which was a bad idea since it would force people
to reinstall boot1 after a 'make world'.

Unfortunately this means that people who have already installed a new
boot1 from a 'make world' after 2000/09/18 *must* reinstall it after
their next build using something like:

        # disklabel -B /dev/da0c
2000-10-27 09:36:34 +00:00
David E. O'Brien
bc6049dd46 Install the loader manpages. 2000-10-26 21:47:59 +00:00
Doug Rabson
d2041924cd Move the call to extend_heap() from main to start so that if our BSS
expands beyond the limit we will extend the address space before trying
to zero the BSS. This should give us plenty of headroom for modest
expansion of the loader.
2000-10-25 23:36:01 +00:00
Doug Rabson
75cdadceb4 Don't build start.S as part of libalpha.a - its built specially. 2000-10-25 23:30:04 +00:00
Doug Rabson
bcdb85b6b8 Don't indirect through a null pointer if we run out of kernel filenames. 2000-10-25 23:28:19 +00:00
Doug Rabson
a3fc4e0754 Make a few functions inline to save space. 2000-10-25 23:24:43 +00:00
Nick Hibma
2fd84f56d5 The USB scanner driver. To be used together with SANE. 2000-10-25 10:34:38 +00:00
David E. O'Brien
c2606cffec Convert from the Alpha compontents to PowerPC ones. 2000-10-16 19:58:32 +00:00
David E. O'Brien
146a7d5318 "Ok, my loader's now up to putting up a prompt. It probes disks partially
but can't boot from them yet."

Thanks to Stephane Potvin for the some of the code in this set.

Submitted by:	Benno Rice <benno@jeamland.net>
2000-10-16 10:46:22 +00:00
Yoshihiro Takahashi
54bb2a24af Merged from sys/boot/i386/loader/main.c revision 1.21. 2000-10-15 02:56:48 +00:00
Daniel C. Sobral
3851401454 Now I see the error of my ways.
Previous revision of this file changed the "boot" commands to take
no arguments from the stack. This is only valid in the case where
a kernel has not been loaded. In that case, load_kernel_and_modules
will be called, which takes a list of arguments from the stack.

When a kernel is presently loaded, though, the list of arguments must
be passed to the boot command, which was the behaviour before the last
revision.

Fix things for both cases.

Noticed by: S-Max and others on that chat room
2000-10-09 11:29:40 +00:00
Robert Nordier
8c964b9bca Go back to occupying just a single sector, reverting r1.17 - r1.20.
Taking over the sector following the MBR causes problems on some
machines, and the actual gains are fairly small in terms of how
the space is presently used.

Since we need a number of further features (eg. handling extended
partitions) that can't be readily accommodated in the basic boot0
design anyway, rather choose to implement the additional stuff
separately and concentrate on compatibility rather than features
here.
2000-10-02 17:30:22 +00:00
Robert Nordier
ce6a6a0f90 Set MAINTAINER. 2000-10-02 17:23:16 +00:00
Daniel C. Sobral
530df9baad Get rid of garbage left on the stack. 2000-09-25 11:36:55 +00:00
Daniel C. Sobral
a360c980c2 What could possibly have possessed me to forget the "0 (arguments)"
in two of the three boot words in the "boot" redefinition, I have no
clue. Fix it.

Noticed by: bp
Noticed by: adrian
2000-09-25 11:18:02 +00:00
KATO Takenori
6473734288 Merged from sys/boot/i386/loader/main.c revision 1.23. 2000-09-22 12:51:22 +00:00
KATO Takenori
87eae000dd Merged from sys/boot/i386/libi386/Makefile revision 1.19. 2000-09-22 12:49:15 +00:00
Archie Cobbs
474afc4230 Add support for the "nullconsole" console type, for systems with
neither a video console nor a serial port. Use it if the RB_MUTE
flag is set.

Submitted by:	Doug Ambrisko <ambrisko@whistle.com>
Reviewed by:	jhb
2000-09-20 18:13:36 +00:00
Daniel C. Sobral
504119265e Check for the correct minimum version required by the current code.
I hope I got this right... :-)
2000-09-18 22:42:54 +00:00
Matt Jacob
81372ff0ed Steal 512KB more from system memory for heap instead of 256KB. We died
without the extra space. What a pity.
2000-09-18 08:19:04 +00:00
Matt Jacob
8c8c7c234b Run SECONDARY_LOAD_ADDRESS down to 0x2000a000- this still leaves
(barely) enough room for boot1 and gives us 8KB more to play with
in the loader.
2000-09-18 08:17:57 +00:00
Matt Jacob
4b3f16308b Make the stack 12K- we seem to need a bit more.
Rename 'stack' to 'stackbase' as this variable
more correctly denotes what it is.
2000-09-18 08:16:38 +00:00
Daniel C. Sobral
818c39998e Use _ instead or - where proper, according to the style I have been
using.

Overload "?" so it will also show loader.4th commands.
2000-09-16 21:04:49 +00:00
Daniel C. Sobral
df3c7d3993 Solve a name clash.
Add something to help debugging.
2000-09-16 20:20:44 +00:00
Daniel C. Sobral
c888e59b84 The default search path for kernel and modules was bogus. It makes no
sense for /boot/kernel to come last.
2000-09-16 19:59:41 +00:00
Daniel C. Sobral
54329571cf The module_path set by default was bogus. It had /boot/kernel last,
which makes little sense.
2000-09-16 19:56:23 +00:00
Daniel C. Sobral
7b9e034490 Both boot and boot-conf were using a different algorithm from the one
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>
2000-09-16 19:49:52 +00:00
Daniel C. Sobral
1cb190742f Factorize, reorganize, and move code around.
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...
2000-09-15 08:05:52 +00:00
Daniel C. Sobral
9f0c5de5f7 Start countdown only _after_ the kernel was loaded. Not very fair otherwise. 2000-09-15 07:54:10 +00:00
Daniel C. Sobral
a708ce6fa3 New world order wrt to kernel location and name. This doesn't actually
changes anything (in theory), just better document it. I'm waiting for
the final word before I tackle the man pages.
2000-09-12 20:21:11 +00:00
Roger Hardiman
6ce5d87513 Back out bktr_mem_load. It is not needed because I'm use MODULE_DEPEND
elsewhere.
Reminded by: Mike Smith
2000-09-12 08:41:55 +00:00
Roger Hardiman
0950aa881d Add bktr_mem_loader, default to NO.
In the near future the bktr module will need the bktr_mem module too.
2000-09-11 10:46:03 +00:00
Doug Rabson
55f0c30072 Fix this so that we actually define HAVE_PNP when its available. 2000-09-10 17:11:27 +00:00
Mark Murray
0f3ad95051 The entropy driver module has changed name. 2000-09-10 13:58:58 +00:00
Daniel C. Sobral
9714dd1a3a Bump up version as a result of the recent changes to kernel path,
and boot-conf&boot semantic changes.

Also, make it 1.0.

Reminded by: peter (even though he doesn't know it)
2000-09-10 13:51:44 +00:00
Daniel C. Sobral
f3b36c2a14 Bump up version as a result of the recent changes to kernel path,
and boot-conf&boot semantic changes.

Reminded by: peter (even though he doesn't know it)
2000-09-10 13:51:31 +00:00
Daniel C. Sobral
2ae7c98e29 Change NOFORTH comment character from # to \ followed by space,
to make things more interchangeable between it and the FORTH case.

Perhaps requiring the space is a bit too much, but...

Nothing in the tree seems to produce loader.rc files with comment
line, at this time.
2000-09-10 13:48:51 +00:00
Doug Rabson
4eedebf31f Only build PnP parts if the platform supports PnP. 2000-09-10 12:15:30 +00:00
Daniel C. Sobral
23aecb0109 Upon reflection, I decided that bootfile must have priority over kernel
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.
2000-09-09 18:20:00 +00:00
Robert Nordier
3348fae50d Correct BSD/OS slice type.
PR:           21099
Submitted by: Alan Clegg <abc@bsdi.com>
2000-09-09 18:05:22 +00:00
Daniel C. Sobral
88a7f9eb70 First tackle at trying to handle the New Deal on kernels.
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.)
2000-09-09 04:52:34 +00:00
Daniel C. Sobral
869e9b2096 Update boot and boot-conf descriptions to reflect new and old changes.
Add a warning in loader(8) that boot might be changed by loader.4th.
2000-09-08 21:39:31 +00:00
Daniel C. Sobral
80a1a63ef5 Enhance boot-conf.
Now boot-conf can also receive parameters to be passed to the kernel
being booted. The syntax is the same as in the boot command, so one
boots /kernel.OLD in single-user mode by typing:

boot-conf /kernel.OLD -s   instead of
boot-conf -s /kernel.OLD

The syntax still supports use of directory instead of file name, so

boot-conf kernel.OLD -s

may be used to boot /boot/kernel.OLD/kernel.ko in single-user mode.

Notice that if one passes a flag to boot-conf, it will override the
flags set in .conf files, but only for that invocation. If the user
aborts the countdown and tries again without passing any flags, the
flags set in .conf files will be used.

Some factorization was done in the process of enhancing boot-conf,
as it has been growing steadly as features are getting added, becoming
too big for a Forth word. It still could do with more factorization,
as a matter of fact.

Override the builtin "boot" with something based on boot-conf. It will
behave exactly like boot-conf, but booting directly instead of going
through autoboot.

Since we are now pairing kernel and module set in the same directory,
this change to boot makes sense.
2000-09-08 21:11:57 +00:00
Daniel C. Sobral
ebc9286d61 Strictly speaking, this works. It enumarates the PnP devices, and
load the modules needed according to a file relating module names
(actually, _file_ names, not really modules -- the dependency
stuff is not exported to loader's UI) to PnP IDs.

But it still lacks a number of desired features, and it's too crude
for my tastes. But since I don't have time to work on it, it might
be preferable to make it available to those who might. It's not
installed by default, much less loaded. In fact, it wouldn't even
had a copyright message (who? me? assume responsibility for _this_?),
if the cvs commit hadn't aborted for lack of $FreeBSD$, and I decided
to just cut&paste the stuff from elsewhere.
2000-09-08 17:13:24 +00:00
Daniel C. Sobral
f5da975f8f Add the infrastructure necessary to handle PnP from a Forth script.
Also, export the file_findfile() function. Again, this is taken from
work in progress but frozen for the time being. Since it works, I'd
rather commit and remove any uglyness later than hide it on my tree.
2000-09-08 17:03:53 +00:00
Daniel C. Sobral
d39b220c77 Fix an error message which was using the wrong variable to get the
kernel name from.
2000-09-08 16:58:31 +00:00
Daniel C. Sobral
297c9cab3e Add constructors to crude structure support. Rework some of the
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.
2000-09-08 16:57:28 +00:00
Daniel C. Sobral
3053524c85 Make the pnp structure a global variable, so it can be used elsewhere. 2000-09-08 16:51:29 +00:00
Daniel C. Sobral
59549c5031 Fix autoboot. Now autoboot *always* show the correct kernel name. It
gets the name from the environment variable kernelname, which is set
when a kernel is loaded. For this reason, autoboot will _first_ try
to load a kernel, and only proceed with the wait prompt after that
succeeds. If it fails, it will abort immediately.

While I understand some may think this behavior undesirable, I think
it is, overall, the best thing to do, even if we do not consider the
aesthetic issue. Notice that anyone using the default loader.rc
already has the kernel loaded before autoboot.

On unload, unset kernelname.

Separate the code that tries to load a kernel from the list of options
to the function loadakernel(). It is used by both boot() and
autoboot().
2000-09-08 16:47:05 +00:00
KATO Takenori
87beee9c90 Merged from sys/boot/i386/loader/Makefile revision 1.47. 2000-09-08 11:18:40 +00:00
Warner Losh
799c0f62dd Look for libstand in the built tree rather than in /usr/lib. This
likely could be done better, but the tree is broken and I wanted to
get a fix into the tree.

Reviewed by: msmith
2000-09-08 04:26:55 +00:00
David E. O'Brien
db266683d3 With the committed changes to the loaders modules path code, the kernel
path does not need to be hard coded.
2000-09-06 20:50:24 +00:00
David E. O'Brien
6f54390e53 Fix the kernel default load from "/boot/modules" to "/boot/kernel".
Reported by:	dcs
2000-09-05 23:10:46 +00:00
David E. O'Brien
3bdfa9e589 The kernel is now known as `kernel.ko' and it and its matching modules
live in ``/boot/kernel/''.
2000-09-05 22:37:46 +00:00
Mike Smith
0153af6a16 Fix a bug which prevents parsing this Makefile without having a
previously-built loader binary elsewhere.
2000-09-05 22:33:07 +00:00
Mike Smith
bb65fdf6e0 Export the salient configuration items in a non-pxe-specific namespace
to allow commonality between varying platforms.  This is a step
towards parsing the diskless configuration information with MI code
inside the kernel.

Export the interface hardware address to the kernel, so that it is possible
to determine the boot interface with certainty.

Export the NFS filehandle for the root mount to the kernel, so that the
kernel does not need to perform a mount RPC call.
2000-09-05 22:32:31 +00:00
David E. O'Brien
06a5e547a9 This is real released software, let people think that. 2000-09-03 02:46:17 +00:00
KATO Takenori
8b6a5e91bb The INT 1B BIOS call is used to obtain geometries of SASI/IDE hard
drives.  Some IDE cards don't set propler information into BIOS work
are and their sector size were always recognized as 256 bytes/sector.

Pointed out by:	jagarl@creator.club.ne.jp
2000-08-31 10:24:06 +00:00
John Baldwin
6bd9abd49a Add a new compile-time tweak to BTX. If you set the make(1) variable
BOOT_BTX_NOHANG, then BTX will be compiled with the appropriate flags so
that it reboots after a fault instead of hanging forever.

Requested by:	ps
Approved by:	rnordier
2000-08-24 20:57:44 +00:00
Sheldon Hearn
243782a80a List loader.conf and friends in the FILES section.
Requested by:	obrien
2000-08-24 08:00:29 +00:00
KATO Takenori
77dff523b3 Fixed determination method for sector size of the 2nd IDE HDD. 2000-08-15 08:17:03 +00:00
KATO Takenori
9300e1bae2 Merged from sys/boot/i386/Makefile.inc revision 1.2. 2000-08-12 07:37:19 +00:00
Peter Wemm
5aef48a16b Add -mpreferred-stack-boundary=2 to CFLAGS for i386. This and libstand
reduces /boot/loader from 163840 bytes to 155648 and pxeboot from 165888
bytes to 157696 bytes.
2000-08-11 23:23:20 +00:00
Daniel C. Sobral
e7b7c050c7 Add missing "is".
PR:		20524
Submitted by:	Peter Pentchev <roam@orbitel.bg>
2000-08-11 10:32:23 +00:00
Paul Saab
646cf5017b Add support to send the string 'PXEClient' as the Vendor class
identifier to the DHCP server.  Now you can check for this string
in your dhcp configuration to decide whether you will hand out a
lease to the client or not.
2000-08-11 08:36:17 +00:00
Paul Saab
f6940c1842 Pass along the interesting variables we were given from DHCP so we
can utilize them in the kernel and with kenv.
2000-08-11 05:31:59 +00:00
Robert Nordier
ff7ed3a234 Typo/spelling fixes. 2000-08-08 07:20:25 +00:00
KATO Takenori
c4082e99a4 - Fixed missing initialization of current device number.
- Fixed comment.

Pointed out by:	nyan
2000-08-06 14:35:37 +00:00
John Baldwin
ab9e9f9d2d Argh! Fix a brainfart of mine. In the old boot0, we relocated ourself
to 0x600 via a 'rep movsw'.  Once that was done, %cx was zero, so we could
simply use 'movb' to update the lower byte of %cx in preparation for
zeroing out the fake partition entry used to boot to other drives via F5.
Well, in the new boot0, we don't actually relocate ourselves, instead it
is easier to create the fake partition entry first and then just use it to
get the BIOS to load all of boot0 into memory at 0x600.  However, since we
aren't doing the relocate code anymore, we don't know that %cx == 0 when
we hit the 'movb' to setup %cx for clearning the fake partition entry.
Thus, if %ch != 0 when the BIOS started boot0, then it would end up zeroing
a lot more memory than just 8 words.  The solution is to do a word move of
$8 into %cx.

Debugging help from:	David Wolfskill <dhw@whistle.com>
2000-08-04 22:37:21 +00:00