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CPU_ROOTCONF(9) NetBSD Kernel Developer's Manual CPU_ROOTCONF(9)
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Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.
cpu_rootconf, rootconf, setroot -- root file system setup
setroot(device_t bootdv, int bootpartition);
The 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. cpu_rootconf() provides the global
variables booted_device, booted_partition, booted_startblk, booted_nblks,
and bootspec. cpu_rootconf invokes the machine-independent function
rootconf which calls the function setroot to record the root device and
the root partition information for use in machine-independent code.
rootconf may adjust the global variables and determines the parameters
for setroot. This is for example used to translate a device and parti-
tion number provided by the bootloader into a disk wedge device covering
the same partition.
If the bootloader already identified a disk wedge, it passes a non-zero
value for booted_nblks, then booted_startblk and booted_nblks specify a
disk wedge as the boot device.
setroot evaluates several sources to identify the root device in the fol-
lowing order until a valid device is selected:
1. The kernel configuration variable rootspec which is set by
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 setroot is used.
2. The variable bootspec following the same syntax.
3. The result of an interactive query of the root device if boothowto
has set the flag RB_ASKNAME. The input uses the same syntax as the
previous sources. Here also the kernel dump device is queried.
4. The boot device and partition passed as arguments.
If a root device cannot be selected, setroot sets the RB_ASKNAME flag and
Otherwise the kernel dump device is identified in a similar manner from
1. The result of a previous interactive query. See above.
2. The kernel configuration variable dumpspec, if set.
3. The second partition of the root device, if it is a regular disk.
4. The first disk wedge device of type DKW_PTYPE_SWAP.
config(1), dk(4), boot(8), boothowto(9)
NetBSD 9.99 November 11, 2014 NetBSD 9.99