On 12/31/22 19:21, H. Peter Anvin wrote:
Alternatively, setup_data could be relocated, the boot param protocol
could be bumped, and then QEMU could conditionalized it's use of
setup_data based on that protocol version. That'd work, but seems a bit
more involved.
I think this is at least worth considering because the kernel overwriting
setup_data after having been told where that setup_data is located is
not really
nice.
Well not explicitly at least - it gets the pointer to the first
element and
something needs to traverse that list to know which addresses are
live. But
still, that info is there so perhaps we need to take setup_data into
consideration too before decompressing...
It would probably be a good idea to add a "maximum physical address for
initrd/setup_data/cmdline" field to struct kernel_info, though. It
appears right now that those fields are being identity-mapped in the
decompressor, and that means that if 48-bit addressing is used, physical
memory may extend past the addressable range.
-hpa