include/exec/memattrs.h

   1 /*
   2  * Memory transaction attributes
   3  *
   4  * Copyright (c) 2015 Linaro Limited.
   5  *
   6  * Authors:
   7  *  Peter Maydell <peter.maydell@linaro.org>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #ifndef MEMATTRS_H
  15 #define MEMATTRS_H
  16
  17 /* Every memory transaction has associated with it a set of
  18  * attributes. Some of these are generic (such as the ID of
  19  * the bus master); some are specific to a particular kind of
  20  * bus (such as the ARM Secure/NonSecure bit). We define them
  21  * all as non-overlapping bitfields in a single struct to avoid
  22  * confusion if different parts of QEMU used the same bit for
  23  * different semantics.
  24  */
  25 typedef struct MemTxAttrs {
  26     /* Bus masters which don't specify any attributes will get this
  27      * (via the MEMTXATTRS_UNSPECIFIED constant), so that we can
  28      * distinguish "all attributes deliberately clear" from
  29      * "didn't specify" if necessary.
  30      */
  31     unsigned int unspecified:1;
  32     /* ARM/AMBA: TrustZone Secure access
  33      * x86: System Management Mode access
  34      */
  35     unsigned int secure:1;
  36     /* Memory access is usermode (unprivileged) */
  37     unsigned int user:1;
  38     /* Requester ID (for MSI for example) */
  39     unsigned int requester_id:16;
  40 } MemTxAttrs;
  41
  42 /* Bus masters which don't specify any attributes will get this,
  43  * which has all attribute bits clear except the topmost one
  44  * (so that we can distinguish "all attributes deliberately clear"
  45  * from "didn't specify" if necessary).
  46  */
  47 #define MEMTXATTRS_UNSPECIFIED ((MemTxAttrs) { .unspecified = 1 })
  48
  49 #endif