.\"     $NetBSD: cpu_rootconf.9,v 1.10 2014/11/26 20:46:46 wiz Exp $
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.\" by Gregory McGarry.
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.Dd November 11, 2014
.Dt CPU_ROOTCONF 9
.Os
.Sh NAME
.Nm cpu_rootconf ,
.Nm rootconf ,
.Nm setroot
.Nd root file system setup
.Sh SYNOPSIS
.In sys/types.h
.In sys/systm.h
.Ft void
.Fn cpu_rootconf "void"
.Ft void
.Fn rootconf "void"
.Ft void
.Fn setroot "device_t bootdv" "int bootpartition"
.Sh DESCRIPTION
The
.Fn cpu_rootconf
is a machine-dependent interface invoked during system bootstrap to
determine the root file system device and initialize machine-dependent
file system state.
.Fn cpu_rootconf
provides the global variables
.Fa booted_device ,
.Fa booted_partition ,
.Fa booted_startblk ,
.Fa booted_nblks ,
and
.Fa bootspec .
.Fa cpu_rootconf
invokes the machine-independent function
.Fa rootconf
which calls the function
.Fa setroot
to record the root device and the root partition information
for use in machine-independent code.
.Pp
.Fa rootconf
may adjust the global variables and determines the parameters
for setroot.
This is for example used to translate a device
and partition number provided by the bootloader into a disk
wedge device covering the same partition.
.Pp
If the bootloader already identified a disk wedge, it passes
a non-zero value for
.Fa booted_nblks ,
then
.Fa booted_startblk
and
.Fa booted_nblks
specify a disk wedge as the boot device.
.Pp
.Fa setroot
evaluates several sources to identify the root device in the
following order until a valid device is selected:
.Bl -enum
.It
The kernel configuration variable
.Fa rootspec
which is set by
.Xr config 1 .
The value is the name and unit of the root device, e.g., "sd0" (disk)
or "dk0" (wedge) or "le0" (network) or the prefix "wedge:" followed
by the name of the disk wedge.
For disk devices the partition passed as argument to
.Fa setroot
is used.
.It
The variable
.Fa bootspec
following the same syntax.
.It
The result of an interactive query of the root device if
.Fa boothowto
has set the flag
.Dv RB_ASKNAME .
The input uses the same syntax as the previous sources.
Here also the kernel dump device is queried.
.It
The boot device and partition passed as arguments.
.El
.Pp
If a root device cannot be selected,
.Fa setroot
sets the
.Dv RB_ASKNAME
flag and loops.
.Pp
Otherwise the kernel dump device is identified in a similar
manner from
.Bl -enum
.It
The result of a previous interactive query.
See above.
.It
The kernel configuration variable
.Fa dumpspec ,
if set.
.It
The second partition of the root device, if it is a regular disk.
.It
The first disk wedge device of type DKW_PTYPE_SWAP.
.El
.Sh SEE ALSO
.Xr config 1 ,
.Xr dk 4 ,
.Xr boot 8 ,
.Xr boothowto 9