anchor.diff:    ${optionalString (!stdenv.is64bit) ''
       HIGHMEM64G? y # We need 64 GB (PAE) support for Xen guest support.
     ''}
  +  INTEL_IOMMU_DEFAULT_ON y
  +  ${optionalString (versionAtLeast version "3.9") ''
  +    VFIO_PCI_VGA y
  +  ''}
  +  VIRT_DRIVERS y
   
     # Media support.
     ${optionalString (versionAtLeast version "3.6") ''
  
positive.code:   CIFS_XATTR y
    CIFS_POSIX y
    CIFS_FSCACHE y
  
    # Security related features.
    STRICT_DEVMEM y # Filter access to /dev/mem
  
negative.code:   IP_DCCP_CCID3 n # experimental
    CLS_U32_PERF y
    CLS_U32_MARK y
    BPF_JIT y
  
    # Wireless networking.
    CFG80211_WEXT? y # Without it, ipw2200 drivers don't build
  