On Fri, 30 Apr 2021 at 10:06, Heiner Kallweit <hkallweit1@xxxxxxxxx> wrote: > > I'm one of the people seeing the following warning: > > efi: memattr: Entry attributes invalid: RO and XP bits both cleared > efi: memattr: ! 0x000000090000-0x000000090fff [Runtime Code|RUN| | | | | | | | | | | | | ] > > Out of curiosity I checked UEFI spec 2.9. On p.108 there's table 4.1: > > EFI_MEMORY_RO EFI_MEMORY_XP EFI_MEMORY_RUNTIME > No memory access protection is possible for Entry 0 0 1 > Write-protected Code 1 0 1 > Read/Write Data 0 1 1 > Read-only Data 1 1 1 > > So it seems to be valid that both attributes are cleared. > Also in the surrounding text I didn't find a hint mandating > that at least one the attributes has to be set. You are right. My assumption at the time was that not having either of RO or XP in the memory attributes table makes little sense, as it describes the default case. However, this interpretation may conflict with the requirement that entries in the memory attributes table cover an entry in the EFI memory map entirely, or not at all. IOW, if a memory map entry consists of a code region, a data region and a region that requires both execute and write permissions, there would be no way to describe it unless we permit entries that have RO and XP both cleared. Patches welcome! -- Ard.
