memory: add readonly support to memory_region_init_ram_from_file()
There is currently no way to open(O_RDONLY) and mmap(PROT_READ) when
creating a memory region from a file. This functionality is needed since
the underlying host file may not allow writing.
Add a bool readonly argument to memory_region_init_ram_from_file() and
the APIs it calls.
Extend memory_region_init_ram_from_file() rather than introducing a
memory_region_init_rom_from_file() API so that callers can easily make a
choice between read/write and read-only at runtime without calling
different APIs.
No new RAMBlock flag is introduced for read-only because it's unclear
whether RAMBlocks need to know that they are read-only. Pass a bool
readonly argument instead.
Both of these design decisions can be changed in the future. It just
seemed like the simplest approach to me.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20210104171320.575838-2-stefanha@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 521d990..c6ce74f 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -966,6 +966,7 @@
* - RAM_PMEM: the memory is persistent memory
* Other bits are ignored now.
* @path: the path in which to allocate the RAM.
+ * @readonly: true to open @path for reading, false for read/write.
* @errp: pointer to Error*, to store an error if it happens.
*
* Note that this function does not do anything to cause the data in the
@@ -978,6 +979,7 @@
uint64_t align,
uint32_t ram_flags,
const char *path,
+ bool readonly,
Error **errp);
/**
