On Fri, Nov 08, 2024 at 09:14:02AM -0500, Steven Sistare wrote: > > Could anyone remind me why we can't simply set PRIVATE|SHARED all over the > > place? > > > > IMHO RAM_AUX is too hard for any new callers to know how to set. It's much > > easier when we already have SHARED, adding PRIVATE could be mostly natural, > > then we can already avoid AUX due to checking !SHARED & !PRIVATE. > > > > Basically, SHARED|PRIVATE then must come from an user request (QMP or > > cmdline), otherwise the caller should always set none of them, implying > > aux. > > > > It still looks the best to me. > > Our emails crossed. We could set PRIVATE|SHARED all over the place. Nothing > wrong with that solution. I have no preference, other than finishing.
The current AUX is exactly what I was picturing when I was replying v2, so the four paths you listed here: https://lore.kernel.org/qemu-devel/44b15731-0ee8-4e24-b4f5-0614bca59...@oracle.com/ Agreed, RAM_AUX is a clear solution. I would set it in these functions: qemu_ram_alloc_resizeable memory_region_init_ram_nomigrate memory_region_init_rom_nomigrate memory_region_init_rom_device_nomigrate That is what I listed previously: https://lore.kernel.org/qemu-devel/Zv7C7MeVP2X8bEJU@x1n/ I think that means below paths [1-4] are only relevant: qemu_ram_alloc memory_region_init_rom_device_nomigrate [1] memory_region_init_ram_flags_nomigrate memory_region_init_ram_nomigrate [2] memory_region_init_rom_nomigrate [3] qemu_ram_alloc_resizeable [4] Except that if we don't want to risk using VM_SHARED unconditionally on linux for aux, then we need to have a new flag, aka RAM_AUX or similar. So I believe the list is at least correct. I changed my mind because I noticed it will be non-trivial to know whether one should set RAM_AUX when a new user needs to create some new ramblocks. In that case, we need to define RAM_AUX properly. One sane way to define it is: "if the user didn't specify share or private property, please use AUX", but then it'll overlap with RAM_SHARED / RAM_PRIVATE already, hence redundant. Yes, let's wait and see David's comment. Thanks, -- Peter Xu
