VBE_DISPI_INDEX_Y_OFFSET
bochs_dispi_write(bochs, VBE_DISPI_INDEX_Y_OFFSET, 0);
bochs_dispi_write(bochs, VBE_DISPI_INDEX_Y_OFFSET, vy);
vbox_write_ioport(VBE_DISPI_INDEX_Y_OFFSET,
[VBE_DISPI_INDEX_Y_OFFSET] = "y-offset",
(u64)vbe[VBE_DISPI_INDEX_Y_OFFSET] * mode->stride);