On 05/04/17 16:52, Gerd Hoffmann wrote: > Hi, > >> If we invent such a new register, it should be in a location that is >> either read-only, or zeroed-on-reset, in current QEMU. Otherwise, new >> firmware running on old QEMU could be misled by a guest OS that writes >> to this register, and then either reboots or enters S3. > > Good point, we need to be quite careful here to not open security holes. > Current state is that pretty much all pci config space is writable and > not cleared on reset. So no easy way out. > >> ... With this in mind, I don't oppose "having to write somewhere to read >> back the result", but then let's please make that write access as well >> to the same new qemu-specific register, and not to MCH_ESMRAMC. > > That should work, yes. Write '1' to the register, then read back. If > it is still '1' -> no big tseg support. Otherwise it returns the tseg > size in some form, and "11b" in ESMRAMC can be used to pick that.
My thoughts exactly! Thank you, Laszlo _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
