At the front is btxldr, in the middle is BTX itself (our mini-kernel), and
then the 'client' (loader.bin) which is the actual loader itself. boot2
just executes a raw ELF or a.out binary with the only setup provided being
that a bootinfo structure is passed on the stack. Now, since loader.bin
is a BTX client, the loader needs to be able to locate a BTX kernel for
the client to execute in the context. Thus, just like pxelder, btxldr
uses the a.out header on the loader binary to find the BTX kernel stored
in the loader and set it up. It does _not_ just reuse the BTX kernel
that boot2 invoked it with. This is because it can't assume that it will
_have_ a "spare" BTX kernel lying around. For example, when cdboot
loads the loader there isn't an existing BTX kernel. In fact, cdboot
will only work with an a.out loader as well since it also "borrows" the
BTX kernel in the loader binary (which it finds by parsing the a.out
header) just as pxeldr does. The only difference between cdboot and
pxeldr is where they get /boot/loader from.
If we wanted to make /boot/loader be an actual ELF binary we would need
to change the following utilites to handle that (and they all have to be
able to handle locating the BTX kernel inside of an ELF binary somehow):
- btxldr
- pxeldr
- cdboot
If we didn't want to require a flag day but make the transition smooth
then we need to be able to support both a.out and ELF versions of
/boot/loader which isn't exactly trivial since all three of these utilities
are written in assembly.
Pointy-hat to: peter
this was quite broken, it never was updated for metadata support.
The a.out kld file support was never really used, as it wasn't necessary.
You could always load elf kld's, even in an a.out kernel.
filesystem expands the inode to 256 bytes to make space for 64-bit
block pointers. It also adds a file-creation time field, an ability
to use jumbo blocks per inode to allow extent like pointer density,
and space for extended attributes (up to twice the filesystem block
size worth of attributes, e.g., on a 16K filesystem, there is space
for 32K of attributes). UFS2 fully supports and runs existing UFS1
filesystems. New filesystems built using newfs can be built in either
UFS1 or UFS2 format using the -O option. In this commit UFS1 is
the default format, so if you want to build UFS2 format filesystems,
you must specify -O 2. This default will be changed to UFS2 when
UFS2 proves itself to be stable. In this commit the boot code for
reading UFS2 filesystems is not compiled (see /sys/boot/common/ufsread.c)
as there is insufficient space in the boot block. Once the size of the
boot block is increased, this code can be defined.
Things to note: the definition of SBSIZE has changed to SBLOCKSIZE.
The header file <ufs/ufs/dinode.h> must be included before
<ufs/ffs/fs.h> so as to get the definitions of ufs2_daddr_t and
ufs_lbn_t.
Still TODO:
Verify that the first level bootstraps work for all the architectures.
Convert the utility ffsinfo to understand UFS2 and test growfs.
Add support for the extended attribute storage. Update soft updates
to ensure integrity of extended attribute storage. Switch the
current extended attribute interfaces to use the extended attribute
storage. Add the extent like functionality (framework is there,
but is currently never used).
Sponsored by: DARPA & NAI Labs.
Reviewed by: Poul-Henning Kamp <phk@freebsd.org>
is turned off by default and could be enabled by defining LOADER_BZIP2_SUPPORT
make variable. Also make gzip support optional (turned on by default) -
it could be turned off via LOADER_NO_GZIP_SUPPORT make variable.
Please note, that due to limit on the amount of memory available to the
loader(8), it is possible to load modules/kernels compressed with the smallest
block size supported by the bzip2 - 100k (`-1' bzip2(1) option), however
even in this mode bzip2(1) usually provides better compression ratio than
gzip(1) in its best compression mode.
MFC after: 1 month
You may specify TFTP or NFS via compile time options in the loader,
but not both at this time.
Also, remove a warning about not knowing how to boot from network
devices. We can obviously do that now.
- Don't hard code 0x10000 as the entry point for the loader. Instead add
src/sys/boot/i386/Makefile.inc which defines a make variable with the
entry point for the loader. Move the loader's entry point up to
0x20000, which makes PXE happy.
- Don't try to use cpp to parse btxldr for the optional BTXLDR_VERBOSE,
instead use m4 to achieve this. Also, add a BTXLDR_VERBOSE knob in the
btxldr Makefile to turn this option on.
- Redo parts of cdldr's Makefile so that it now builds and installs cdboot
instead of having i386/loader/Makefile do that. Also, add in some more
variables to make the pxeldr Makefile almost identical and thus to ease
maintainability.
- Teach cdldr about the a.out format. Cdldr now parsers the a.out header
of the loader binary and relocates it based on that. The entry point of
the loader no longer has to be hardcoded into cdldr. Also, the boot
info table from mkisofs is no longer required to get a useful cdboot.
- Update the lsdev function for BIOS disks to parse other file systems
(such as DOS FAT) that we currently support. This is still buggy as
it assumes that a floppy with a DOS boot sector actually has a MBR and
parses it as such. I'll be fixing this in the future.
- The biggie: Add in support for booting off of PXE-enabled network
adapters. Currently, we use the TFTP API provided by the PXE BIOS.
Eventually we will switch to using the low-level NIC driver thus
allowing both TFTP and NFS to be used, but for now it's just TFTP.
Submitted by: ps, alfred
Testing by: Benno Rice <benno@netizen.com.au>
- Fix btxldr to preserve a NULL bootinfo pointer when it copies the kernel
arguments.
- Add the cdldr bootstrap program. This program is tacked onto the
beginning of the standard 3rd stage boot loader (/boot/loader) to form
the CD boot loader (/boot/cdboot). When a CD is booted, the cdboot file
is copied into memory instead and executed. The cdldr stub emulates the
environment normally provided by boot2 and then starts the loader. This
booting method does not emulate a floppy drive, but boots directly off of
the CD. This should fix the problems some BIOS's have with emulating a
2.88 MB floppy image.
- Add support to the loader to recognize that it has been booted by cdldr
instead of boot2 and use a simpler method of extracting the BIOS boot
device.
needs. This removes the dependancy on Perl for the generation of the
loader, allowing the world to be built on a perl-free system.
Submitted by: Joe Abley <jabley@clear.co.nz>
Note no matching commit for the Alpha, as the alpha boot0 stage does
not have the ability to prompt for user input.
PR: kern/9406
Submitted by: "Daniel C. Sobral" <dcs@newsguy.com>
- Use the ISA PnP enumerator.
- Use the new linker set code, throw out the gensetdefs stuff.
- Produce an intermediate loader image that has symbols stripped, to aid
- in debugging.
- Supply ISA port access functions required for ISA PnP
