Merge remote-tracking branch 'remotes/philmd/tags/memory-api-20220118' into staging

Memory API patches

- Directly dispatch MemoryRegion alias accesses
- Remove duplicated Address Space information in 'info mtree'
- Cleanups around memory_region_is_mapped()
- Fix incorrect calls of log_global_start/stop()
- Use dma_addr_t type definition when relevant
- Let dma_buf_read() / dma_buf_write() propagate MemTxResult
- Clarify MemoryRegion aliases documentation

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* remotes/philmd/tags/memory-api-20220118:
  docs/devel: add some clarifying text for aliases
  hw/dma: Let dma_buf_read() / dma_buf_write() propagate MemTxResult
  hw/dma: Use dma_addr_t type definition when relevant
  hw/dma: Move ScatterGatherEntry / QEMUSGList declarations around
  hw/dma: Fix format string issues using dma_addr_t
  hw/scsi: Rename SCSIRequest::resid as 'residual'
  hw/rdma/rdma_utils: Rename rdma_pci_dma_map 'len' argument
  hw/dma: Remove CONFIG_USER_ONLY check
  hw/pci: Document pci_dma_map()
  hw/pci: Restrict pci-bus stub to sysemu
  hw/nvram: Restrict fw_cfg QOM interface to sysemu and tools
  stubs: Restrict fw_cfg to system emulation
  memory: Fix incorrect calls of log_global_start/stop
  memory: Update description of memory_region_is_mapped()
  memory: Make memory_region_is_mapped() succeed when mapped via an alias
  machine: Use host_memory_backend_is_mapped() in machine_consume_memdev()
  memory: Have 'info mtree' remove duplicated Address Space information
  memory: Split mtree_info() as mtree_info_flatview() + mtree_info_as()
  memory: Directly dispatch alias accesses on origin memory region

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 9 insertions, 5 deletions

diff --git a/docs/devel/memory.rst b/docs/devel/memory.rst
index 5dc8a12682..69c5e3f914 100644
--- a/docs/devel/memory.rst
+++ b/docs/devel/memory.rst
@@ -67,11 +67,15 @@ MemoryRegion):
 
   You initialize a pure container with memory_region_init().
 
-- alias: a subsection of another region.  Aliases allow a region to be
-  split apart into discontiguous regions.  Examples of uses are memory banks
-  used when the guest address space is smaller than the amount of RAM
-  addressed, or a memory controller that splits main memory to expose a "PCI
-  hole".  Aliases may point to any type of region, including other aliases,
+- alias: a subsection of another region. Aliases allow a region to be
+  split apart into discontiguous regions. Examples of uses are memory
+  banks used when the guest address space is smaller than the amount
+  of RAM addressed, or a memory controller that splits main memory to
+  expose a "PCI hole". You can also create aliases to avoid trying to
+  add the original region to multiple parents via
+  `memory_region_add_subregion`.
+
+  Aliases may point to any type of region, including other aliases,
   but an alias may not point back to itself, directly or indirectly.
   You initialize these with memory_region_init_alias().