man2/cacheflush.2

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  25 .TH CACHEFLUSH 2 2017-09-15 "Linux" "Linux Programmer's Manual"
  26 .SH NAME
  27 cacheflush \- flush contents of instruction and/or data cache
  28 .SH SYNOPSIS
  29 .nf
  30 .B #include <asm/cachectl.h>
  31 .PP
  32 .BI "int cacheflush(char *" addr ", int "nbytes ", int "cache );
  33 .fi
  34 .SH DESCRIPTION
  35 .BR cacheflush ()
  36 flushes the contents of the indicated cache(s) for the
  37 user addresses in the range
  38 .I addr
  39 to
  40 .IR (addr+nbytes-1) .
  41 .I cache
  42 may be one of:
  43 .TP
  44 .B ICACHE
  45 Flush the instruction cache.
  46 .TP
  47 .B DCACHE
  48 Write back to memory and invalidate the affected valid cache lines.
  49 .TP
  50 .B BCACHE
  51 Same as
  52 .BR (ICACHE|DCACHE) .
  53 .SH RETURN VALUE
  54 .BR cacheflush ()
  55 returns 0 on success or \-1 on error.
  56 If errors are detected,
  57 .I errno
  58 will indicate the error.
  59 .SH ERRORS
  60 .TP
  61 .B EFAULT
  62 Some or all of the address range
  63 .I addr
  64 to
  65 .I (addr+nbytes-1)
  66 is not accessible.
  67 .TP
  68 .B EINVAL
  69 .I cache
  70 is not one of
  71 .BR ICACHE ,
  72 .BR DCACHE ,
  73 or
  74 .BR BCACHE
  75 (but see BUGS).
  76 .SH CONFORMING TO
  77 Historically, this system call was available on all MIPS UNIX variants
  78 including RISC/os, IRIX, Ultrix, NetBSD, OpenBSD, and FreeBSD
  79 (and also on some non-UNIX MIPS operating systems), so that
  80 the existence of this call in MIPS operating systems is a de-facto
  81 standard.
  82 .SS Caveat
  83 .BR cacheflush ()
  84 should not be used in programs intended to be portable.
  85 On Linux, this call first appeared on the MIPS architecture,
  86 but nowadays, Linux provides a
  87 .BR cacheflush ()
  88 system call on some other architectures, but with different arguments.
  89 .SH BUGS
  90 Linux kernels older than version 2.6.11 ignore the
  91 .I addr
  92 and
  93 .I nbytes
  94 arguments, making this function fairly expensive.
  95 Therefore, the whole cache is always flushed.
  96 .PP
  97 This function always behaves as if
  98 .BR BCACHE
  99 has been passed for the
 100 .I cache
 101 argument and does not do any error checking on the
 102 .I cache
 103 argument.