3f38115c7b
. define _MINIX_SYSTEM for all system code from minix.service.mk . hide some system-level declarations and definitions behind _MINIX_SYSTEM to cleanly fix host tool build problems on Minix (such as: NONE being defined and paddr_t being used but not declared) . the similar definition _SYSTEM is unsuitable as it changes the values of errno definitions Change-Id: I407de79e2575115243a074b16e79546a279cfa3e
76 lines
3.1 KiB
C
76 lines
3.1 KiB
C
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#ifndef _MINIX_ENDPOINT_H
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#define _MINIX_ENDPOINT_H 1
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#ifdef _MINIX_SYSTEM
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#include <minix/sys_config.h>
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#include <minix/com.h>
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#include <limits.h>
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#include <minix/type.h>
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/*
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* Endpoints are split into two parts: a process slot and a generation number.
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*
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* The process slot number identifies the slot in various process tables.
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* It is positive or zero for user processes, and negative for kernel tasks.
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* Constants dictate that with the current endpoint layout, the maximum range
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* of process slot numbers is [-MAX_NR_TASKS,MAX_NR_PROCS>. The used part of
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* the range is currently [-NR_TASKS,NR_PROCS> -- these two constants may be
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* changed within the maximum range without changing the endpoint layout.
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*
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* The generation number is a per-slot number that gets increased by one every
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* time a slot is reused for a new process. The generation number minimizes
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* the chance that the endpoint of a dead process can (accidentially) be used
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* to communicate with a different, live process. Preventing such accidents
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* is essential for proper system service restartability support.
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*
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* The split between the two parts of the endpoint is such that when the
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* generation number is zero, the endpoint number equals the process slot
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* number, even for negative task numbers. This is required for the endpoint
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* numbers hardcoded in <minix/com.h>, and it makes endpoint numbers easy to
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* read in general.
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*
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* There are three special endpoint numbers: ANY, NONE, and SELF. These
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* numbers are used to identify "any process", "no process at all", and
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* "own process", respectively. They fall outside the normal range of
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* process slot numbers, and are always of generation zero.
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*/
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/*
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* The following constant defines the split between the two parts of the
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* endpoint numbers. It can be adjusted to allow for either more processes
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* or more per-process generation numbers. Changing it will change the
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* endpoint number layout, and thus break binary compatibility with existing
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* processes.
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*/
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#define _ENDPOINT_GENERATION_SHIFT 15
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/* Derived constants. */
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#define _ENDPOINT_GENERATION_SIZE (1 << _ENDPOINT_GENERATION_SHIFT)
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/* INT_MAX is used here to prevent signedness issues with the macros below. */
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#define _ENDPOINT_MAX_GENERATION (INT_MAX/_ENDPOINT_GENERATION_SIZE-1)
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#define _ENDPOINT_SLOT_TOP (_ENDPOINT_GENERATION_SIZE-MAX_NR_TASKS)
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/* The special endpoint numbers, and the resulting maximum slot number. */
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#define ANY ((endpoint_t) (_ENDPOINT_SLOT_TOP - 1))
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#define NONE ((endpoint_t) (_ENDPOINT_SLOT_TOP - 2))
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#define SELF ((endpoint_t) (_ENDPOINT_SLOT_TOP - 3))
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#define MAX_NR_PROCS (_ENDPOINT_SLOT_TOP - 3) /* (int)SELF */
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/* Sanity check. */
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#if NR_PROCS > MAX_NR_PROCS
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#error "NR_PROCS exceeds MAX_NR_PROCS, increase _ENDPOINT_GENERATION_SHIFT"
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#endif
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/* Generation + Process slot number <-> endpoint. */
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#define _ENDPOINT(g, p) \
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((endpoint_t)(((g) << _ENDPOINT_GENERATION_SHIFT) + (p)))
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#define _ENDPOINT_G(e) (((e)+MAX_NR_TASKS) >> _ENDPOINT_GENERATION_SHIFT)
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#define _ENDPOINT_P(e) \
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((((e)+MAX_NR_TASKS) & (_ENDPOINT_GENERATION_SIZE - 1)) - MAX_NR_TASKS)
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#endif /* _MINIX_SYSTEM */
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#endif
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