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* Memory transaction attributes
* Copyright (c) 2015 Linaro Limited.
* Authors:
* Peter Maydell <>
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
#ifndef MEMATTRS_H
#define MEMATTRS_H
/* Every memory transaction has associated with it a set of
* attributes. Some of these are generic (such as the ID of
* the bus master); some are specific to a particular kind of
* bus (such as the ARM Secure/NonSecure bit). We define them
* all as non-overlapping bitfields in a single struct to avoid
* confusion if different parts of QEMU used the same bit for
* different semantics.
typedef struct MemTxAttrs {
/* Bus masters which don't specify any attributes will get this
* (via the MEMTXATTRS_UNSPECIFIED constant), so that we can
* distinguish "all attributes deliberately clear" from
* "didn't specify" if necessary.
unsigned int unspecified:1;
/* ARM/AMBA: TrustZone Secure access
* x86: System Management Mode access
unsigned int secure:1;
/* Memory access is usermode (unprivileged) */
unsigned int user:1;
* Bus interconnect and peripherals can access anything (memories,
* devices) by default. By setting the 'memory' bit, bus transaction
* are restricted to "normal" memories (per the AMBA documentation)
* versus devices. Access to devices will be logged and rejected
unsigned int memory:1;
/* Requester ID (for MSI for example) */
unsigned int requester_id:16;
/* Invert endianness for this page */
unsigned int byte_swap:1;
* The following are target-specific page-table bits. These are not
* related to actual memory transactions at all. However, this structure
* is part of the tlb_fill interface, cached in the cputlb structure,
* and has unused bits. These fields will be read by target-specific
* helpers using env->iotlb[mmu_idx][tlb_index()].attrs.target_tlb_bitN.
unsigned int target_tlb_bit0 : 1;
unsigned int target_tlb_bit1 : 1;
unsigned int target_tlb_bit2 : 1;
} MemTxAttrs;
/* Bus masters which don't specify any attributes will get this,
* which has all attribute bits clear except the topmost one
* (so that we can distinguish "all attributes deliberately clear"
* from "didn't specify" if necessary).
#define MEMTXATTRS_UNSPECIFIED ((MemTxAttrs) { .unspecified = 1 })
/* New-style MMIO accessors can indicate that the transaction failed.
* A zero (MEMTX_OK) response means success; anything else is a failure
* of some kind. The memory subsystem will bitwise-OR together results
* if it is synthesizing an operation from multiple smaller accesses.
#define MEMTX_OK 0
#define MEMTX_ERROR (1U << 0) /* device returned an error */
#define MEMTX_DECODE_ERROR (1U << 1) /* nothing at that address */
#define MEMTX_ACCESS_ERROR (1U << 2) /* access denied */
typedef uint32_t MemTxResult;