geteminor(D3DK) —

.IX \f4geteminor\fP(D3DK)

NAME

geteminor − get external minor device number .IX minor device number, external

SYNOPSIS

#include <sys/types.h>
#include <sys/ddi.h>
minor_t geteminor(dev_t dev);

ARGUMENTS

devExternal device number.

DESCRIPTION

geteminor returns the external minor number given a device number, dev. External minor numbers are visible to the user. Internal minor numbers are only visible in the kernel. Since a driver can support more than one external major device that map to the same internal major device, the kernel keeps a mapping between external minor numbers and internal minor numbers to allow drivers to index arrays more easily. For example, a driver may support two devices, each with five minor numbers. The user may see each set of minor numbers numbered from zero to four, but the driver sees them as one set of minor numbers numbered from zero to nine.

All driver entry points are passed device numbers using external minor numbers.

Systems that map external major device numbers one-to-one with internal major numbers also map external minor numbers one-to-one with internal minor numbers.

RETURN VALUE

The external minor number.

LEVEL

Base or Interrupt.

NOTES

Does not sleep.

Driver-defined basic locks, read/write locks, and sleep locks may be held across calls to this function.

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