of the ..umm.. "wierd" way binutils lays out the file. The section
headers are nearly at the end of the file and this is a problem when
loading from a .gz file which can't seek backwards (or has a limited
reverse seek, ~2K from memory).
This is intended to be compatable with the ddb/db_elf.c code and the
alpha/libalpha/elf_freebsd.c layout. I've studied these (which are NetBSD
derived) but did it a bit differently. Naturally the process is similar
since it's supposed to end up with the same result.
bootblocks, the kernel shows up as the primary module:
[3:24am]~-100# kldstat
Id Refs Address Size Name
1 1 0xf0100000 ff00000 /kernel
^^^^ oops.. :-)
Based heavily on aout_freebsd.c. Hmm.. There's so much in common that
these could probably be combined and just check the metadata to see which
format it is.
so far, and should probably be able to be made to work for the alpha
without too much trouble once it's connected up and my assumptions tested.
I think (but have not tested) it will also load "old" ELF kernels that
were not linked with DYNAMIC headers.
The module glue is yet to come. (oh fun.. :-)
It does not explicitly load symbols [yet]. The _DYNAMIC data contains a
runtime symbol set that ddb can use via ddb/db_kld.c. It'll be missing
some detail that stabs normally provides (eg: number of args to a function,
line numbers, etc). On the other hand, those minimal symbols will always
be available even on a stripped kernel.
This is mostly stolen from load_aout.c with some ideas from
alpha/libalpha/elf_freebsd.c.
Presumably VTOP doesn't work for static objects.
The easiest way to get it working was to reserve some space after the
environment strings and copy the bootinfo struct there.
Also, set RB_BOOTINFO, it's needed.
I got the code to load and run an unmolested kernel OK for the first time
with this system a few minutes ago - at last!. I did have to stop it
looking at the floppy though as BTX was trapping a mode 14 fault when
it look for /boot/boot.conf when no disk was in the drive. (I'm booting
from a scsi disk (bios disk 0x80)).
Now to teach it about ELF and modules :-)
* Fix a raft of warnings, printf and otherwise.
* Allocate the correct amount in mod_searchmodule to prevent an overflow.
* Fix the makefiles so they work outside my home directory (oops).
Allow the MI code to override the preferred console (eg. so that
an RB_SERIAL flag from the i386 boot2 can override the default
first active console)
isapnp.c
Use the standard format for ISA PnP IDs.
pnp.c
Allow trailing comments on lines, be less picky about line
contents.
ls.c
Cosmetic error message fix.
panic.c
Print the right arguments.
- Make the "what do we do with a drunken disklabel" if-then-else-regardless
tangle easier to read.
- Don't count on the v86 structure being preserved between loop iterations,
as it may be trampled eg. by the DEBUG call.
- Discard large amounts of BIOS-related code in favour of the more compact
BTX vm86 interface.
- Build the loader module as ELF, although the resulting object is a.out,
make gensetdefs 32/64-bit sensitive and use a single copy of it.
- Throw away installboot, as it's no longer required.
- Use direct bcopy operations in the i386_copy module, as BTX
maps the first 16M of memory. Check operations against the
detected size of actual memory.
- Use format-independant module allocator.
- Conditionalise ISA PnP support.
- Simplify PnP enumerator interface.
- Improve module/object searching.
- Add missing depend/install targets in BTX makefiles.
- Pass the kernel environment and module data in extended bootinfo fields.
- Add a pointer to the end of the kernel + modules in bootinfo.
- Fix parsing of old-style kernel arguments.
- Move some startup code from MD to MI sections
- Add a 'copyout' and some copyout-related functions. These will be
obsoleted when BTX is available for the 386 and the kernel load
area becomes directly addressable.
- Add the ability load an arbitrary file as a module, associating
and arbitrary type string with it. This can be used eg. for loading
splash-screen images etc.
- Add KLD module dependancy infrastructure. We know how to look for
dependancies inside KLD modules, how to resolve these dependancies
and what to do if things go wrong. Only works for a.out at the
moment, due to lack of an MI ELF loader. Attach KLD module information
to loaded modules as metadata, but don't pass it to the kernel (it
can find it itself).
- Load a.out KLD modules on a page boundary. Only pad the a.out BSS
for the kernel, as it may want to throw symbols away. (We might want
to do this for KLD modules too.)
- Allow commands to be hidden from the '?' display, to avoid cluttering
it with things like 'echo'. Add 'echo'.
- Bring the 'prompt' command into line with the parser syntax.
- Fix the verbose 'ls'; it was using an uninitialised stack variable.
- Add a '-v' flag to 'lsmod' to have it display module metadata as well
(not terribly useful for the average user)
- Support a 'module searchpath' for required modules.
- The bootstrap file on i386 is now called 'loader' to permit the
/boot directory to use that name.
- Discard the old i386 pread() function, as it's replaced by
arch_readin()
- Implement a new copyin/readin interface for loading modules.
This allows the module loaders to become MI, reducing code duplication.
- Simplify the search for an image activator for the loaded kernel.
- Use the common module management code for all module metadata.
- Add an 'unload' command that throws everything away.
- Move the a.out module loader to MI code, add support for a.out
kld modules.
Submitted by: Alpha changes fixed by Doug Rabson <dfr@freebsd.org>
'three-stage' bootstrap.
There are a number of caveats with the code in its current state:
- The i386 bootstrap only supports booting from a floppy.
- The kernel and kld do not yet know how to deal with the extended
information and module summary passed in.
- PnP-based autodetection and demand loading of modules is not implemented.
- i386 ELF kernel loading is not ready yet.
- The i386 bootstrap is loaded via an ugly blockmap.
On the alpha, both net- and disk-booting (SRM console machines only) is
supported. No blockmaps are used by this code.
Obtained from: Parts from the NetBSD/i386 standalone bootstrap.
'three-stage' bootstrap.
There are a number of caveats with the code in its current state:
- The i386 bootstrap only supports booting from a floppy.
- The kernel and kld do not yet know how to deal with the extended
information and module summary passed in.
- PnP-based autodetection and demand loading of modules is not implemented.
- i386 ELF kernel loading is not ready yet.
- The i386 bootstrap is loaded via an ugly blockmap.
On the alpha, both net- and disk-booting (SRM console machines only) is
supported. No blockmaps are used by this code.
Obtained from: Parts from the NetBSD/i386 standalone bootstrap.
