exec: qemu_ram_alloc_resizeable, qemu_ram_resize

Add API to allocate "resizeable" RAM.
This looks just like regular RAM generally, but
has a special property that only a portion of it
(used_length) is actually used, and migrated.

This used_length size can change across reboots.

Follow up patches will change used_length for such blocks at migration,
making it easier to extend devices using such RAM (notably ACPI,
but in the future thinkably other ROMs) without breaking migration
compatibility or wasting ROM (guest) memory.

Device is notified on resize, so it can adjust if necessary.

qemu_ram_alloc_resizeable allocates this memory, qemu_ram_resize resizes
it.

Note: nothing prevents making all RAM resizeable in this way.
However, reviewers felt that only enabling this selectively will
make some class of errors easier to detect.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Michael S. Tsirkin
2014-11-12 14:27:41 +02:00
parent 9b8424d573
commit 62be4e3a50
3 changed files with 91 additions and 7 deletions

View File

@ -28,12 +28,19 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
MemoryRegion *mr, Error **errp);
ram_addr_t qemu_ram_alloc(ram_addr_t size, MemoryRegion *mr, Error **errp);
ram_addr_t qemu_ram_alloc_resizeable(ram_addr_t size, ram_addr_t max_size,
void (*resized)(const char*,
uint64_t length,
void *host),
MemoryRegion *mr, Error **errp);
int qemu_get_ram_fd(ram_addr_t addr);
void *qemu_get_ram_block_host_ptr(ram_addr_t addr);
void *qemu_get_ram_ptr(ram_addr_t addr);
void qemu_ram_free(ram_addr_t addr);
void qemu_ram_free_from_ptr(ram_addr_t addr);
int qemu_ram_resize(ram_addr_t base, ram_addr_t newsize, Error **errp);
static inline bool cpu_physical_memory_get_dirty(ram_addr_t start,
ram_addr_t length,
unsigned client)