On 08/05/22 14:47, Jason A. Donenfeld wrote: > Hi Paolo, > > On Fri, Aug 05, 2022 at 10:10:02AM +0200, Paolo Bonzini wrote: >> On 8/5/22 01:04, Jason A. Donenfeld wrote: >>> + /* Nothing else uses this part of the hardware mapped region */ >>> + setup_data_base = 0xfffff - 0x1000; >> >> Isn't this where the BIOS lives? I don't think this works. > > That's the segment dedicated to ROM and hardware mapped addresses. So > that's a place to put ROM material. No actual software will use it.
... accordingly (I think), when the guest tries to read it, it will see the ROM MemoryRegion that QEMU places there, not RAM contents. "info mtree" QEMU monitor command output (excerpt), while OVMF is in the Boot Device Selection phase (well, I left it waiting in the Setup TUI): address-space: memory 0000000000000000-ffffffffffffffff (prio 0, i/o): system 0000000000000000-000000007fffffff (prio 0, ram): alias ram-below-4g @pc.ram 0000000000000000-000000007fffffff 0000000000000000-ffffffffffffffff (prio -1, i/o): pci 00000000000a0000-00000000000affff (prio 2, ram): alias vga.chain4 @vga.vram 0000000000000000-000000000000ffff 00000000000a0000-00000000000bffff (prio 1, i/o): vga-lowmem 00000000000c0000-00000000000dffff (prio 1, rom): pc.rom 00000000000e0000-00000000000fffff (prio 1, rom): isa-bios flat view ("info mtree -f"): FlatView #1 AS "memory", root: system AS "cpu-memory-0", root: system AS "cpu-memory-1", root: system AS "cpu-memory-2", root: system AS "cpu-memory-3", root: system AS "mch", root: bus master container AS "ICH9-LPC", root: bus master container AS "ich9-ahci", root: bus master container AS "ICH9-SMB", root: bus master container AS "pcie-root-port", root: bus master container AS "pcie-root-port", root: bus master container AS "pcie-root-port", root: bus master container AS "pcie-root-port", root: bus master container AS "pcie-root-port", root: bus master container AS "qemu-xhci", root: bus master container AS "virtio-scsi-pci", root: bus master container AS "virtio-serial-pci", root: bus master container AS "virtio-net-pci", root: bus master container AS "VGA", root: bus master container AS "virtio-balloon-pci", root: bus master container AS "virtio-rng-pci", root: bus master container Root memory region: system 0000000000000000-000000000002ffff (prio 0, ram): pc.ram KVM 0000000000030000-000000000004ffff (prio 1, i/o): smbase-blackhole 0000000000050000-000000000009ffff (prio 0, ram): pc.ram @0000000000050000 KVM 00000000000a0000-00000000000affff (prio 1, ram): vga.vram KVM 00000000000b0000-00000000000bffff (prio 1, i/o): vga-lowmem @0000000000010000 00000000000c0000-00000000000c3fff (prio 0, rom): pc.ram @00000000000c0000 KVM 00000000000c4000-00000000000dffff (prio 1, rom): pc.rom @0000000000004000 KVM 00000000000e0000-00000000000fffff (prio 1, rom): isa-bios KVM Laszlo