1cacheflush(2)                 System Calls Manual                cacheflush(2)
2
3
4

NAME

6       cacheflush - flush contents of instruction and/or data cache
7

LIBRARY

9       Standard C library (libc, -lc)
10

SYNOPSIS

12       #include <sys/cachectl.h>
13
14       int cacheflush(void addr[.nbytes], int nbytes, int cache);
15
16       Note:  On some architectures, there is no glibc wrapper for this system
17       call; see NOTES.
18

DESCRIPTION

20       cacheflush() flushes the contents of the  indicated  cache(s)  for  the
21       user  addresses in the range addr to (addr+nbytes-1).  cache may be one
22       of:
23
24       ICACHE Flush the instruction cache.
25
26       DCACHE Write back to memory and invalidate  the  affected  valid  cache
27              lines.
28
29       BCACHE Same as (ICACHE|DCACHE).
30

RETURN VALUE

32       cacheflush()  returns  0  on success.  On error, it returns -1 and sets
33       errno to indicate the error.
34

ERRORS

36       EFAULT Some or all of the address range addr to (addr+nbytes-1) is  not
37              accessible.
38
39       EINVAL cache is not one of ICACHE, DCACHE, or BCACHE (but see BUGS).
40

VERSIONS

42       cacheflush()  should  not  be used in programs intended to be portable.
43       On Linux, this call first appeared on the MIPS architecture, but  nowa‐
44       days, Linux provides a cacheflush() system call on some other architec‐
45       tures, but with different arguments.
46
47   Architecture-specific variants
48       glibc provides a wrapper for this system call, with the prototype shown
49       in  SYNOPSIS,  for  the  following  architectures: ARC, CSKY, MIPS, and
50       NIOS2.
51
52       On some other architectures, Linux provides this system call, with dif‐
53       ferent arguments:
54
55       M68K:
56              int cacheflush(unsigned long addr, int scope, int cache,
57                             unsigned long len);
58
59       SH:
60              int cacheflush(unsigned long addr, unsigned long len, int op);
61
62       NDS32:
63              int cacheflush(unsigned int start, unsigned int end, int cache);
64
65       On  the  above architectures, glibc does not provide a wrapper for this
66       system call; call it using syscall(2).
67
68   GCC alternative
69       Unless you need the finer grained control that this  system  call  pro‐
70       vides,   you   probably   want   to   use  the  GCC  built-in  function
71       __builtin___clear_cache(), which provides a portable  interface  across
72       platforms supported by GCC and compatible compilers:
73
74           void __builtin___clear_cache(void *begin, void *end);
75
76       On   platforms   that   don't   require   instruction   cache  flushes,
77       __builtin___clear_cache() has no effect.
78
79       Note: On some GCC-compatible compilers, the prototype for this built-in
80       function uses char * instead of void * for the parameters.
81

STANDARDS

83       Historically,  this system call w