It takes the following options, which set flags in the boothowto variable in the booted kernel:
RB_ASKNAME
)
Cause the kernel to prompt the user for the name of the device containing the
root filesystem. This also causes
boot26
to prompt for the name of the kernel to be loaded.
RB_SINGLE
)
Cause the kernel to ask
init
to boot into single-user mode.
RB_KDB
)
Cause the kernel to enter the kernel debugger as soon as possible.
RB_USERCONF
)
Enter the in-kernel device configuration manager before attaching any
devices.
RB_QUIET
)
Cause the kernel to emit fewer messages than normal while starting up.
RB_VERBOSE
)
Cause the kernel to emit more messages than normal while starting up.
boot26
attempts to load the kernel from the RISC OS file specified as
file,
or from
netbsd
if
file
is not specified. The file must be an ELF image, and may have been compressed
using
gzip(1).
It should also be possible to arrange for boot26 to be loaded from ROM (e.g. from the ROM on an expansion card), in which case NetBSD could be made to boot automatically by making boot26 the configured language using `*Configure Language'.
0 -> zero-page
+ -> boot26 workspace
* -> Free space (boot26 wants to put the kernel here)
d -> RAM disc
s -> System sprite area
m -> RMA
h -> System heap/stack
f -> Font cache
S -> Screen memory
On a machine with 32k pages (which is all NetBSD/acorn26 supports), the left half of the first line is potential screen memory, and hence not used by . The next page is usually zero page under RISC OS, and is used for zero page under NetBSD as well. The next is usually the system heap under RISC OS, and is used for process 0's kernel stack under NetBSD. The next is used for the message buffer under NetBSD. Pages from there on are used to load the kernel, and must be free if boot26 is to do so successfully. Future bootloaders should load the kernel into whatever pages are free, then kick out RISC OS and shuffle them into the right shape. This is left as an exercise for the enthusiastic reader.
/usr/mdec/boot26,ffa