From 20bccb82ff3ea09bcb7c4ee226d3160cab15f7da Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 24 Oct 2016 16:26:49 +0100 Subject: cpu: Support a target CPU having a variable page size Support target CPUs having a page size which isn't knownn at compile time. To use this, the CPU implementation should: * define TARGET_PAGE_BITS_VARY * not define TARGET_PAGE_BITS * define TARGET_PAGE_BITS_MIN to the smallest value it might possibly want for TARGET_PAGE_BITS * call set_preferred_target_page_bits() in its realize function to indicate the actual preferred target page size for the CPU (and report any error from it) In CONFIG_USER_ONLY, the CPU implementation should continue to define TARGET_PAGE_BITS appropriately for the guest OS page size. Machines which want to take advantage of having the page size something larger than TARGET_PAGE_BITS_MIN must set the MachineClass minimum_page_bits field to a value which they guarantee will be no greater than the preferred page size for any CPU they create. Note that changing the target page size by setting minimum_page_bits is a migration compatibility break for that machine. For debugging purposes, attempts to use TARGET_PAGE_SIZE before it has been finally confirmed will assert. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson --- include/hw/boards.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/hw/boards.h') diff --git a/include/hw/boards.h b/include/hw/boards.h index e46a744bcd..a51da9c440 100644 --- a/include/hw/boards.h +++ b/include/hw/boards.h @@ -86,6 +86,12 @@ typedef struct { * Returns a @HotpluggableCPUList, which describes CPUs objects which * could be added with -device/device_add. * Caller is responsible for freeing returned list. + * @minimum_page_bits: + * If non-zero, the board promises never to create a CPU with a page size + * smaller than this, so QEMU can use a more efficient larger page + * size than the target architecture's minimum. (Attempting to create + * such a CPU will fail.) Note that changing this is a migration + * compatibility break for the machine. */ struct MachineClass { /*< private >*/ @@ -124,6 +130,7 @@ struct MachineClass { ram_addr_t default_ram_size; bool option_rom_has_mr; bool rom_file_has_mr; + int minimum_page_bits; HotplugHandler *(*get_hotplug_handler)(MachineState *machine, DeviceState *dev); -- cgit v1.2.3-55-g7522