// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.sysmem;

/// "SyM"
const uint32 SYSMEM_METADATA_TYPE = 0x53794d64; // 0x53794d00 | DEVICE_METADATA_PRIVATE

struct SysmemMetadata {
    uint32 vid;
    uint32 pid;

    // protected_memory_size
    // contiguous_memory_size
    //
    // Positive values are interpreted as bytes, and are aligned up to next
    // ZX_PAGE_SIZE.
    //
    // Negative values are interpreted as a percentage of physical memory (after
    // negation), and resulting size in bytes is aligned up to next ZX_PAGE_SIZE.

    // protected_memory_size
    //
    // Size of the protected memory pool.  See above for how this value is
    // interpreted.
    //
    // 0 means there is no protected memory pool.
    int64 protected_memory_size;

    // contiguous_memory_size
    //
    // Size of the pool used to allocate contiguous memory.  See above for how
    // this value is interpreted.
    //
    // Zero means no space is reserved up front, which will end up using
    // zx::vmo::create_contiguous() for each allocation instead of allocating up
    // front, which can be prone to failure when physical memory becomes
    // fragmented.
    //
    // There is no fallback from pre-reserved to zx::vmo::create_contiguous().
    // If we're pre-reserving memory, we should reserve enough.
    int64 contiguous_memory_size;
};