On Mon, Jan 16, 2023 at 11:56:48AM +0100, Gerd Hoffmann wrote: > On Sat, Jan 14, 2023 at 01:20:24AM +0300, Kirill A. Shutemov wrote: > > On Fri, Jan 13, 2023 at 09:29:26PM +0000, Dionna Glaze wrote: > > > This patch depends on Kirill A. Shutemov's series > > > > > > [PATCHv8 00/14] mm, x86/cc: Implement support for unaccepted memory > > > > > > The UEFI v2.9 specification includes a new memory type to be used in > > > environments where the OS must accept memory that is provided from its > > > host. Before the introduction of this memory type, all memory was > > > accepted eagerly in the firmware. In order for the firmware to safely > > > stop accepting memory on the OS's behalf, the OS must affirmatively > > > indicate support to the firmware. > > > > I think it is a bad idea. > > > > This approach breaks use case with a bootloader between BIOS and OS. > > As the bootloader does ExitBootServices() it has to make the call on > > behalf of OS when it has no idea if the OS supports unaccepted. > > Nothing breaks, it'll error on the safe side. If the protocol callback > is not called the firmware will simply accept all memory. The guest OS > will only see unaccepted memory if it explicitly asked for it (assuming > the firmware wants know to support both cases, of course the firmware > could also enforce the one or the other and just not offer the > protocol). How bootloader suppose to know if OS will ask for unaccepted memory? It can't. It means the use-case with bootloader cannot ever use unaccepted memory. That's broken design. -- Kiryl Shutsemau / Kirill A. Shutemov
