Saved a few bytes by copying `dosdev' and/or `name' to local variables.
This optimization (for dosdev) was done in one place before but this
was lost in the devread() cleanup. This optimization (for dosdev)
can almost be done by bogusly declaring dosdev as const, but gcc still
often space-pessimizes code like the following:
extern const int dosdev; ... foo(dosdev); bar(dosdev);
gcc often doesn't bother to copy dosdev to a temporary local because
the local would have to be preserved in memory across the call to
foo(). OTOH, for
extern int dosdev; ... auto int dosdev_copy = dosdev; ...
foo(dosdev_copy); bar(dosdev_copy);
the copy must be made because foo() might alter dosdev.
the pointer to the string "/kernel". This pointer was once only
statically to once save space, but it has had to be dynamically
initialized for some time, so the static initialization just wastes
space. The string gets moved to the text section, so the actual
savings may be negative due to padding.
- avoiding strcmp("?" saved 12 bytes. gcc inlined the strcmp()
but this takes as much or more code as a function call. The
inlining was bogus because the strcmp() in the bootstrap isn't
standard.
- using a char instead of an int for the boolean `last_only' saved 8
bytes. Booleans should usually be represented as chars on the i386.
- simplifying the return tests saved 9 bytes.
- using putc instead of printf to print a newline saved 3 bytes of code
and 2 bytes of const data.
- avoiding `else's by always doing the else clause and fixing it up
saved 4+8 bytes.
gcc always generates large code for accesses to globals. For locals
it only generates large code if there are more than 128 bytes of
locals. It sorts scalar locals after array locals to pessimize for
space in the usual case when there are more (static) references to
scalars than to arrays.
Saved another 16 bytes (13 before padding) by adding a `continue'.
Fall-through tests normally save space, but here one of them made
gcc do space-unoptimal register allocation (it allocates ch in %bl
because preserving this register across function calls is "free",
but comparisions with %bl take one byte fewer than comparsions with
%bl).
I just couldn't get the code to be as small as it should have gotten..
atill a LITTLE bigger than before as I need to allow the
default string to have options as well
1/ Makefile: the maximum size for boot2 is 7.5K not 7K,
so don't complain until it reaches THAT size..
newfs leaves 8K and boot 1 is 512k. leaving 7.5K becasue the disklabel
is considered to part of the boot2 file.
[512 boot1][512 disklabel][ 7K boot2 code ]
[boot1 file][ boot2 file ]
2/ Boot2.S: move the soring of the default name read from block 2 to AFTER
clearing the BSS.
3/ boot.c:
Move the parsing of the command line into the
place it's called for clarity.. alsoi comment it a bit and clean it
up a bit.. for some reason this seems ot have made it a little
larger, but I can't work out why.. maybe bruce might have ideas?
compensated for by shrinkage elsewhere..
the practical result of this is htat the default string can now contain args
e.g. if you change the default string to have -gd
then the machine will boot to the dgb debugger stub by default..
this is mostly useful with the nextboot utility..
as it now allows you to remotely force a machine to reboot into
the debugger.
is only appropriate to use in the special environment of start.S (real
mode plus some conventions about not saving registers), and asm.h is
supposed to be for generic macros.
Removed some unnecessary parentheses.
Add code to the boot blocks to allow the user to place default boot strings
on block 1 of the disk (2nd block), should the correct magic numbers be present.
If the correct options are used it will 'delete' the name used from block1,
thereby assuring that if the boot fails it won't be stuck in an infinite loop.
the boot strings are set by the utility "nextboot"
(not yet checked in, but being tested.)
By default these changes should have no effect on existing installations
and if compiled without the NAMEBLOCK option should be essentially identical
to the old ones.
hd essentially wired the FreeBSD drive number to 0 without changing
the BIOS drive number. Now the numbers can be specified independently.
Replaced the BOOT_HD compile time flag with with BOOT_HD_BIAS. Defining
the new flag as 1 should give the same behaviour as defining the old
flag as anything. I haven't tested defining these flags.
is defined and FORCE_COMCONSOLE isn't defined.
Don't compile any keyboard probing code if PROBE_KEYBOARD isn't defined.
Makefile:
Removed -I paths. They weren't used, and the one to /sys hasn't worked
since the source directory was moved down one level.
counter instead of the BIOS time call to save space.
Reworked the anti-noise timeout to avoid duplicating code. The timeout
in the outer loop is now restarted after every noise timeout, so it is
now possible for the total timeout to be infinite; previously, the maximum
total timeout was 150000 seconds.
must have limit 0xffff and attribute G = 0 (byte granularity) as well
as other properties that they already had (see e.g., the Intel i486
manual section 22.5). Not restoring them broke Ctrl-Alt-Del in the
bootstrap for my ASUS P55TP4XE system, probably because the Award BIOS
does anti-tracing stuff involving inaccessible %esp's.
asm.S:
Don't use lret in prot_to_real(). This reduces the risk of using an
incompletely intialized stack segment and saves space.
Submitted by: "K.Higashino" <a00303@cc.hc.keio.ac.jp> (on 13 Jan 1995!)
reworked by me
boot to display "Booting the kernelel...done" instead of "Booting
the kernel".
Removed save and restore of BIOS memory. kzipped kernels haven't
ever overlaid the BIOS memory.
ignore and set it to 18 sectors/track. This allows FreeBSD to boot with
2.88MB floppies which are used in older ThinkPads.
Submitted by: Random Net person whose name I lost
Claim the major numbers (before sombedoy else jumps in again and
claims the slots for his foocd driver :-), install all the hooks that
are required.
While i've been at this, i've cleaned up some of the routines at the
end of i386/conf.c; all the importers of the latest CDROM drivers
forgot to fill in the appropriate information. The `ata' driver
(vapourware?) does only occupy a slot in the bdevsw[] array, btw.
The actual import of the code does require a minor change in the SCSI
subsystem, and i want to have this reviewed by Peter first, so it will
be deferred for some days. The driver is already working for me
though.
Submitted by: akiyama@kme.mei.co.jp (Shunsuke Akiyama)
user has entered a bogus kernel name in the first place).
Also fix the broken #ifdef FORCE_COMCONSOLE, it has been disabled by
accident. (NB: the keyboard probe remains disabled however.)
Few cosmetic fixes (declare functions to be void instead of int),
while i've been at this.
Pointed out by: wosch@cs.tu-berlin.de (Wolfram Schneider), for the init bug
serial_putchar() always hung if it was called and the serial port existed,
so booting with -h hung when the above bug was fixed. Previously, setting
-h did nothing but -h was sometimes the default due to the stack garbage
bug.
Submitted by: DI. Christian Gusenbauer <cg@scotty.edvz.uni-linz.ac.at>
The `howto' arg to boot() was not supplied, so it was stack garbage (actually
the return address in the boot program). I didn't use the submitted fix.
Change the interfaces of these functions to save space. The code
that takes the least amount of space is often the opposite to what
you might expect. E.g., it helps to waste a few bytes passing
pointers so that the compiler can't see that certain addresses
are identical (gcc likes to waste space by reloading fat constants
even when the constant is already in a register).
Rewrite getbootdev() to save 80 bytes of space and to make it less
ugly. 32 bytes were saved simply by omitting the continue statements
in the pseudo-switch.
recently introduced bloat in just 2 calls to biosread(), although
very little in calls to putc() and serial_putc(). Gcc produces
amazingly bad code for unnecessary conversions. E.g., if it has
`int x' in register %edx and wants to pass a char, then it could
simply push %edx and access only one byte in the callee. Instead,
it sometimes unnecessarily spills %edx; it always sign extends
%edx and pushes the result.
Remove useless `extern' in function prototypes.
Remove unused declaration of `end'.
Declare pbzero() and pcpy() like the library bzero and bcopy().
Declare printf() properly.
do fit, and beeping in case of an overflow.
. Drop a comment about the ``FORCE_COMCONSOLE'' option into
README.serial.
. Increase the name buffer for the root directory from 100 bytes
to 8 KB; this is in no way ideal, but (IMHO) the best that can
be done by now. People did encounter problems with their root
dir name listing overflowing the allocated buffer space. Once
we've got the three-stage boot, we should implement some basic
malloc(). Swap space is already getting tight now, perhaps the
swap should go into another 64 KB segment instead.
. Make the keyboard probe less paranoid. It should not give up in
case of a keyboard that's continuously demanding RESEND's. Even
though the keyboard reset apparently has not been reported to be
complete, it's at the very least proven that there IS something
like a keyboard available.
This solves problems with the ``Gateway-2000 AllKey programmable''
(sp?) keyboard, that experienced a total hang with the previous
probe.
Thanks goes to Scott Blachowicz <scott@statsci.com> for his
extensive testing of my various interim (debugging) bootblocks
to get this working.
interested parties.
Make the loader refuse to load anything below 1 MB -- we didn't
support it since FreeBSD 2.0R. Avoid gratuitously wiping out the BIOS
variables or the loader.
o Fix the keyboard probe to properly wait for the ready bit before
sending a command to the keyboard controller. This should avoid the
problems some people are experiencing where the boot blocks hang the
system during keyboard probe. (It does solve it for me.)
o Fix a bug that effectively prevented the boot blocks from ever
passing control to the serial console. [while(--retries) instead of
while(retries--)]
o Gratuitously reduced the keyboard probe timeout from 500 to 5
seconds. :)
o Introduced a new option ``FORCE_COMCONSOLE'' as a commented-out
example in the Makefile, to force the usage of a serial console
regardless of a keyboard being connected or not.
o Moved all external declarations to boot.h, declared all functions
there, and ANSIfied all function declarations/definitions.
(printf() remains bogus, however -- i'm too lazy to fix this.)
We're in the ninetees, dunno why we should still support compilers
from the 70's.
at least one user out there who's system won't autoboot from the
serial console because of what sounds like 'phantom keystrokes'
making the timeout timer trip. I've tried to solve this by
adding an extra call to init_serial() right before the 'Boot:'
prompt is printed (done only if RB_SERIAL is set) to hopefully
make sure that the input buffer is clear. Unfortunately, the fellow
is in Germany and I haven't heard back from him yet. I haven't
been able to duplicate this problem on my hardware, so this is
a stab in the dark. At the very least, it shouldn't hurt anything.
I'm not exactly sure why all the inb/outw stuff got added to netboot.h
and I'd be happy if someone like Martin or Bruce could take a look at it!
Submitted by: "Serge A. Babkin" <babkin@hq.icb.chel.su>
Install the biosboot as /usr/mdec/boot[12]
Make the traditional links from [swf]dboot and boot[swf]d to boot[12] files.
Install dosboot as /usr/mdec/boot/fbsdboot.exe
Feb. 10th snapshot. The keyboard probe in the bootblock seems to
have been singled out as the cause of these problems, so I've beefed it
up alittle. This pushes us right up to the edge of the size limit:
the second stage boot is now 7152 bytes in size, just 8 bytes under
the wire. On the other hand, the new probe now does almost exactly
what syscons does, so hopefully this will do the trick. It seems
to work properly on my hardware, but then so did the old probe.
