boot(8) - NetBSD Manual Pages

BOOT26(8)           NetBSD/acorn26 System Manager's Manual           BOOT26(8)


NAME

     boot26 -- Bootloader for NetBSD/acorn26


SYNOPSIS

     *boot26 [-acdqsv] [file]


DESCRIPTION

     boot26 is a program that runs under RISC OS and launches the
     NetBSD/acorn26 kernel.  It needs to be installed in a RISC OS filesystem
     and given file type FFA (Module).  The kernel it is to load also needs to
     be stored in a RISC OS filesystem.

     It takes the following options, which set flags in the boothowto variable
     in the booted kernel (see boothowto(9)):

     -a          (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.

     -s          (RB_SINGLE) Cause the kernel to ask init to boot into single-
                 user mode.

     -d          (RB_KDB) Cause the kernel to enter the kernel debugger as
                 soon as possible.

     -c          (RB_USERCONF) Enter the in-kernel device configuration man-
                 ager before attaching any devices.

     -q          (RB_QUIET) Cause the kernel to emit fewer messages than nor-
                 mal while starting up.

     -v          (RB_VERBOSE) Cause the kernel to emit more messages than nor-
                 mal 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).

   Use as a module
     boot26 is implemented as a RISC OS relocatable module.  It can be loaded
     into memory by running `*RMLoad boot26'.  After this, NetBSD can be
     booted by running `*boot26' as usual, but the command will be handled by
     the module.

     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'.

   Screen display
     When it starts up, boot26 displays the current memory map.  Each charac-
     ter in the map represents one page of (physical) RAM.  The ticks along
     the top are to stop you getting lost.  The characters in the map indicate
     what the memory's being used for (actually where it's logically mapped):

           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 boot26.  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.


FILES

     /usr/mdec/boot26,ffa              The location of boot26 in the NetBSD
                                       filesystem.


SEE ALSO

     gzip(1), reboot(2), ddb(4), userconf(4), init(8), boothowto(9)


HISTORY

     boot26 was introduced in NetBSD 1.6 as a replacement for the original
     NetBSD/arm26 bootloader, which was written in BBC BASIC.


BUGS

     boot26 cannot load kernels from a NetBSD filesystem.

NetBSD 7.0                     September 4, 2009                    NetBSD 7.0