#!/bin/sh
# DF-5468 — demonstrate that the ROM path of vga_pci_map_bios() is dead on
# spec-conformant devices: the PCI ROM BAR enable bit (bit 0, RW per spec)
# survives the 0xffffffff sizing readback, and DF's lazy pci_alloc_map()
# then classifies the BAR as an I/O BAR (PCI_BAR_IO(testval)==1), so the
# SYS_RES_MEMORY allocation for rid PCIR_BIOS always fails.
#
# Run as root on the DragonFly QEMU guest.  Harmless: the BAR is restored.
#
# Expected output:
#   testval=0xffff0001   <- enable bit set => PCI_BAR_IO => misclassified
#   and (via the df5467 KLD or a drm attach) dmesg shows:
#       vgapci0: vga_pci_alloc_resource failed
#
VGA=pci0:0:2:0
echo "current ROM BAR (0x30): $(pciconf -r $VGA 0x30)"
pciconf -w $VGA 0x30 0xffffffff
echo "sizing readback       : $(pciconf -r $VGA 0x30)"
pciconf -w $VGA 0x30 0xfebc0000
echo "restored              : $(pciconf -r $VGA 0x30)"
echo
echo "kernel-side proof (unseeded vga_pci_map_bios attempt):"
dmesg | grep -E "vga_pci_alloc_resource failed" | tail -3
echo
echo "bit0 of the readback is the ROM decode-enable bit (RW per PCI spec);"
echo "pci_alloc_map() (sys/bus/pci/pci.c:3933-3966) runs PCI_BAR_MEM(testval)"
echo "on exactly this value and rejects the SYS_RES_MEMORY request."