instructions more (many cases were already intended to be byte-sized
but were missing prefixes so gas assembled them bogusly), and
rearranging a loop to test at the end.
and bios.S were small enough and have been merged back into their
respective files in biosboot/, conditionalized on CDBOOT. Other
files might be merged at a later stage.
Caveat emptor: i cannot test this right now.
This is the long-threatened ISO 9660 CD-ROM bootstrap code.
This work has been sponsored by Plutotech International, Inc (who paid
the initial work), and interface business GmbH (where i did most of
the work). A big thanks also goes to Bruce Evans, for his continuing
help and answering my stupid questions.
The code is basically functioning, with the following caveats:
. Rock Ridge attributes are not yet supported.
. Only SCSI CD-ROMs are supported, since i fail to see any possibility
to determine the drive type using BIOS functions. (Even for hard disks,
this determination is done by a big hack only.)
. El Torito specifies a lot of crap and useless misfeatures, but crucial
things like the ability to figure out the CD TOC have been ``forgotten''.
Thus, if you wanna boot a multisession CD, you need to know at which CD
block your session starts, and need to speciffy it using the @ clause.
. None of the CD-ROM controllers i've seen so far implements the full
El Torito specification at all. Adaptec is probably the closest, but
they miss on non-emulation booting (which would be the most logical
choice for us). Thus, the current code bloats the 7.5 KB boot code
up to 1.44 MB, in order to fake a `floppy' image.
If you wanna use it, specify this file as the boot image on the
command-line of the mksiosfs command (option -b).
Caveat emptor: some versions of the Adaptec BIOS might even fail to
access the CD-ROM at all, using the BIOS functions. I think i've
notice this for ver 1.26, the code has been tested with ver 1.23.
The boot string is as follows:
[@sess-start] [filename] [-flags]
sess-start Extend # where the last session starts, measured in
CD-ROM blocks.
filename As usual, but the input is case-insensitive by now
(since we don't grok RR anyway).
flags As usual, but -C (use CDROM root f/s) is default, so
specifying -C will decactivate this option (which is
probably not what you want :).
A lot of cleanup work is probably required, and some of the files
could/should be merged back to biosboot, perhaps made conditional on
some #ifdef. The malloc implementation that comes with cdboot might
also be useful for kzipboot. (I needed a malloc() since the root dir
ain't fixed in size on a CD.)
I've been testing all this with a 2.2-STABLE as the base for biosboot.
I don't expect too many surprises, although i know the biosboot stuff
has been changed a lot in -current lately. I'm sure Bruce will
comment on all this here anyway. :-)
This work has been sponsored by Plutotech International, Inc (who paid
the initial work), and interface business GmbH (where i did most of
the work). A big thanks also goes to Bruce Evans, for his continuing
help and answering my stupid questions.
The code is basically functioning, with the following caveats:
. Rock Ridge attributes are not yet supported.
. Only SCSI CD-ROMs are supported, since i fail to see any possibility
to determine the drive type using BIOS functions. (Even for hard disks,
this determination is done by a big hack only.)
. El Torito specifies a lot of crap and useless misfeatures, but crucial
things like the ability to figure out the CD TOC have been ``forgotten''.
Thus, if you wanna boot a multisession CD, you need to know at which CD
block your session starts, and need to speciffy it using the @ clause.
. None of the CD-ROM controllers i've seen so far implements the full
El Torito specification at all. Adaptec is probably the closest, but
they miss on non-emulation booting (which would be the most logical
choice for us). Thus, the current code bloats the 7.5 KB boot code
up to 1.44 MB, in order to fake a `floppy' image.
If you wanna use it, specify this file as the boot image on the
command-line of the mksiosfs command (option -b).
Caveat emptor: some versions of the Adaptec BIOS might even fail to
access the CD-ROM at all, using the BIOS functions. I think i've
notice this for ver 1.26, the code has been tested with ver 1.23.
The boot string is as follows:
[@sess-start] [filename] [-flags]
sess-start Extend # where the last session starts, measured in
CD-ROM blocks.
filename As usual, but the input is case-insensitive by now
(since we don't grok RR anyway).
flags As usual, but -C (use CDROM root f/s) is default, so
specifying -C will decactivate this option (which is
probably not what you want :).
A lot of cleanup work is probably required, and some of the files
could/should be merged back to biosboot, perhaps made conditional on
some #ifdef. The malloc implementation that comes with cdboot might
also be useful for kzipboot. (I needed a malloc() since the root dir
ain't fixed in size on a CD.)
I've been testing all this with a 2.2-STABLE as the base for biosboot.
I don't expect too many surprises, although i know the biosboot stuff
has been changed a lot in -current lately. I'm sure Bruce will
comment on all this here anyway. :-)
will see it. The name of the file is obtained by appending ".config"
to the name of the kernel file. If the file doesn't exist, then an
annoying message is printed.
Reduced the command line buffer size yet again from 4096 to 1024. It is
oversized to defend against overrun in gets(), but data space is starting
to run out so the buffer size can't be as grossly oversized as before.
- Added support for "dual" internal/serial consoles (-D flag). If -D is set,
then all i/o from the boot blocks is to and from both the internal console
and the serial console. -D has no effect on the kernel (-h decides the
kernel serial console as usual). -D should normally be set in /boot.config.
- Get help messages from /boot.help. You should copy boot.help from the
biosboot directory to the root directory on the boot drive when you
install new boot blocks.
- New, less invasive keyboard probe. Enable keyboard probe dynamically (-P
flag). Should probably never be used (use -h instead).
- Fixed/improved initialization from boot.config. It didn't interact correctly
with the NAMEBLOCK option, and the initialization of the drive/unit/partition
didn't stick when a non-default kernel name was entered.
- Don't reset or forget the default drive/unit/... or kernel name so often.
- Set the default kernel name to something unbootable after `?'.
- Display the defaults better.
- Removed PROBE_KEYBOARD_LOCK option (use -h instead).,
- Removed BOOT_FORCE_COMCONSOLE option (use device flag 0x20 instead).
- Removed -a (RB_HALT) flag. This flag is only used for reboots.
Submitted by: about 2/3 by yokota
then all i/o from the boot blocks is to and from both the internal console
and the serial console. -D has no effect on the kernel (-h decides the
kernel serial console as usual). -D should normally be set in /boot.config.
- Get help messages from /boot.help. You should copy boot.help from the
biosboot directory to the root directory on the boot drive when you
install new boot blocks.
- New, less invasive keyboard probe. Enable keyboard probe dynamically (-P
flag). Should probably never be used (use -h instead).
- Fixed/improved initialization from boot.config. It didn't interact correctly
with the NAMEBLOCK option, and the initialization of the drive/unit/partition
didn't stick when a non-default kernel name was entered.
- Don't reset or forget the default drive/unit/... or kernel name so often.
- Set the default kernel name to something unbootable after `?'.
- Display the defaults better.
- Removed PROBE_KEYBOARD_LOCK option (use -h instead).,
- Removed BOOT_FORCE_COMCONSOLE option (use device flag 0x20 instead).
- Removed -a (RB_HALT) flag. This flag is only used for reboots.
Submitted by: about 2/3 by yokota
- gcc assumes that %ecx and %edx are clobbered (due to calling
conventions), thus there is no need for saving/restoring those two
registers.
- %es is reset to default value by real_to_prot, thus there is no need
for saving/restorig that register.
Submitted by: tegge
- TFTP is not needed any longer.
Add some other improvements:
- swapsize is now detected if no value was specified.
- resvport is used by default
- merged code for setting/showing mount options for root/swap.
Submitted by: Luigi Rizzo <luigi@labinfo.iet.unipi.it>
"boot.config" (relative to the root directory on the 'a' partition
on the first BSD slice) if it exists. If it doesn't exist, then
the only visible changes should be that the kernel name isn't reset
to "/kernel" after looking it up fails and that the default name
is now "kernel".
The new function readfile() can be used for other things:
- reading help messages.
- reading splash screens.
- reading userconfig info.
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.
They were garbage that happened to be 0 in many cases. (real_to_prot()
happens to leave the value of the real-mode %cr0 in %eax and the
memory-size BIOS calls usually don't touch the upper bits of %eax.
The upper 16 bits of %cr0 are usually 0 at boot time, at least on
486's.
Should be in 2.2.
makerom checksum check calculation was a no-op
nb8390.c had a bug which caused packet_len to be incorrect
for packets which wrapped in the buffer.
Submitted by: Linux developers (I lost the email with their names)
partition is 0, which is outside the slice unless the disk is
dangerously dedicated. There is little error checking later, and
following garbage metadata outside the slice usually caused crashes,
Empty 'a' partitions are fairly easy to create by cloning the label
for the whole disk.
Fixed a missing newline in a related error message.
the keyboard IO port definitions from <machine/console.h>.
Note: I do not have a machine available to test this yet, I sent this
for review to several people who have not replied.
This is also totally busted in 2.2, which has half of the syscons/psm/kbdio
changes in it. This really desperately needs to be tested and fixed
in 2.2 as well.
for get_diskinfo(), whose BIOS call sets %es:%edi in some cases, although
most documentation says that it doesn't change %edi in the cases that
happened to matter (for hard disks).
This shall be in 2.1.6 and 2.2.
Submitted by: Tor.Egge@idt.ntnu.no
(except I kept the unnecessary preservation of %edx and %ecx)
shipped with freebsd can be changed without modifying the Makefiles directly.
Creates: BOOT_FORCE_COMCONSOLE
BOOT_PROBE_KEYBOARD
BOOT_PROBE_KEYBOARD_LOCK
BOOT_COMCONSOLE (port value for console)
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
