Skylake

Skylake

Last edited: Febuary 18, 2020

Starting Point

So making a config.plist may seem hard, its not. It just takes some time but this guide will tell you how to configure eveything, you won't be left in the cold. This also means if you have issues, review your config settings to make sure they're correct. Main things to note with OpenCore:

  • All properties must be defined, there are no default OpenCore will fall back on so do not delete sections unless told explicitly so. If the guide doesn't mention the option, leave it at default.

  • The Sample.plist cannot be used As-Is, you must configure it to your system

  • DO NOT USE CONFIGURATORS, these rarely respect OpenCore's configuration and even some like Mackie's will add Clover properties and corrupt plists!

Now with all that, we'll need some things to get started:

  • ProperTree: For editing our config, this editor has some super useful tools for OpenCore

  • GenSMBIOS: For generating our SMBIOS

  • Sample.plist: This is found under the Docs folder of the release download

Now with those downloaded, we can get to really get started:

  • Grab the Sample.plist and rename to config.plist

  • Open your new config.plist in ProperTree

    • macOS: ProperTree.command

    • Windows: ProperTree.bat

  • Run the Clean Snapshot function(Cmd/Ctrl + Shift + R and point it at your EFI/OC folder),

    • This will remove all the entries from the config.plist and then adds all your SSDTs, Kexts and Firmware drivers to the config

    • Cmd+R is another option that will add all your files as well but will leave entries disabled if they were set like that before, useful for when you're troubleshooting

And read this guide more than once before setting up OpenCore and make sure you have it set up correctly. Do note that images will not always be the most up-to-date so please read the text below them, if nothing's mentioned then leave as default.

ACPI

ACPI

Add:

This is where you'll add SSDTs for your system, these are very important to booting macOS and have many uses like USB maps, disabling unsupported GPUs and such. And with our system, its even required to boot. Guide on making them found here: Getting started with ACPI

For us we'll need a couple of SSDTs to bring back functionality that Clover provided:

  • SSDT-PLUG

    • Allows for native CPU power management on Haswell and newer, Clover alternative would be under Acpi -> GenerateOptions -> PluginType

  • SSDT-EC-USBX

    • Hides the Embedded controller and creates a fake one for macOS, needed for all Catalina users and recommended for other versions of macOS

    • This SSDT also has a second function, USBX. This is used for forcing USB power properties, requires SSDT-EC so this just jumbles them together.

Note that you should not add your generated DSDT.aml here, it is already in your firmware. So if present, remove the entry for it in your config.plist and under EFI/ACPI.

For those wanting a deeper dive into dumping your DSDT, how to make these SSDTs, and compiling them, please see the Getting started with ACPI page. Compiled SSDTs have a .aml extension(Assembled) and will go into the EFI/OC/ACPI folder and must be specified in your config under ACPI -> Add as well.

Block

This blocks certain ACPI tabes from loading, for us we can ignore this

Patch:

This section allows us to dynamically modify parts of the ACPI (DSDT, SSDT, etc.) via OpenCore. For us, our patches are handled by our SSDTs. This is a much cleaner solution as this will allow us to boot Windows and other OSes with OpenCore

Quirk:

Settings relating to ACPI, leave everything here as default.

  • FadtEnableReset: NO

    • Enable reboot and shutdown on legacy hardware, not recommended unless needed

  • NormalizeHeaders: NO

    • Cleanup ACPI header fields, only relevant for macOS High Sierra 10.13

  • RebaseRegions: NO

    • Attempt to heuristically relocate ACPI memory regions, not needed unless custom DSDT is used.

  • ResetHwSig: NO

    • Needed for hardware that fails to maintain hardware signature across the reboots and cause issues with waking from hibernation

  • ResetLogoStatus: NO

    • Workaround for OEM Windows logo not drawing on systems with BGRT tables.

Booter

Booter

This section is dedicated to quirks relating to boot.efi patching with FwRuntimeServices, the replacement for AptioMemoryFix.efi

MmioWhitelist:

This section is allowing devices to be passthrough to macOS that are generally ignored, for us we can ignore this section.

Quirks:

Settings relating to boot.efi patching and firmware fixes, default will work for us

  • AvoidRuntimeDefrag: YES

    • Fixes UEFI runtime services like date, time, NVRAM, power control, etc

  • DevirtualiseMmio: NO

    • Reduces Stolen Memory Footprint, expands options for slide=N values

  • DisableSingleUser: NO

  • Disables the use of Cmd+S and -s, this is closer to the behaviour of T2 based machines

  • DisableVariableWrite: NO

    • Needed for systems with non-functioning NVRAM

  • DiscardHibernateMap: NO

    • Reuse original hibernate memory map, only needed for certain legacy hardware

  • EnableSafeModeSlide: YES

    • Allows for slide values to be used in Safemode

  • EnableWriteUnprotector: YES

    • Removes write protection from CR0 register during their execution

  • ForceExitBootServices: NO

    • Ensures ExitBootServices calls succeeds even when MemoryMap has changed, don't use unless necessary

  • ProtectCsmRegion: NO

    • Needed for fixing artifacts and sleep-wake issues, AvoidRuntimeDefrag resolves this already so avoid this quirk unless necessary

  • ProvideCustomSlide: YES

    • If there's a conflicting slide value, this option forces macOS to use a pseudo-random value. Needed for those receiving Only N/256 slide values are usable! debug message

  • SetupVirtualMap: YES

    • Fixes SetVirtualAddresses calls to virtual addresses

  • ShrinkMemoryMap: NO

    • Needed for systems with large memory maps that don't fit, don't use unless necessary

  • SignalAppleOS: NO

    • Tricks the hardware into thinking its always booting macOS, mainly benifitial for MacBook Pro's with dGPUs as booting Windows won't allow for the iGPU to be used

DeviceProperties

DeviceProperties

Add: Sets device properties from a map.

This section is set up via Headkaze's Intel Framebuffer Patching Guide and applies only one actual property to begin, which is the ig-platform-id. The way we get the proper value for this is to look at the ig-platform-id we intend to use, then swap the pairs of hex bytes.

If we think of our ig-plat as 0xAABBCCDD, our swapped version would look like DDCCBBAA

The two ig-platform-id's we use are as follows:

  • 0x19120000 - this is used when the iGPU is used to drive a display

    • 00001219 when hex-swapped

  • 0x19120001 - this is used when the iGPU is only used for computing tasks and doesn't drive a display

    • 01001219 when hex-swapped

We also add 2 more properties, framebuffer-patch-enable and framebuffer-stolenmem. The first enables patching via WhateverGreen.kext, and the second sets the min stolen memory to 19MB. This is usually unnecessary, as this can be configured in BIOS(64 or 96MB recommended).

PciRoot(0x0)/Pci(0x1f,0x3) -> Layout-id

  • Applies AppleALC audio injection, you'll need to do your own research on which codec your motherboard has and match it with AppleALC's layout. AppleALC Supported Codecs.

For us, we'll be using the boot-arg alcid=xxx instead to accomplish this. alcid will override all other layout-IDs present

Block: Removes device properties from map, for us we can ignore this

Fun Fact: The reason the byte order is swapped is due to Endianness, specifically Little Endians that modern CPUs use for ordering bytes. The more you know!

Kernel

Kernel

Add: Here's where you specify which kexts to load, order matters here so make sure Lilu.kext is always first! Other higher priority kexts come after Lilu such as VirtualSMC, AppleALC, WhateverGreen, etc. A reminder that ProperTree users can run Cmd/Ctrl + Shift + R to add all their kexts in the correct order without manually typing each kext out.

  • BundlePath

    • Name of the kext

    • ex: Lilu.kext

  • Enabled

    • Self-explanatory, either enables or disables the kext

  • ExecutablePath

    • Path to the actual executable is hidden within the kext, you can see what path your kext has by right-clicking and selecting Show Package Contents. Generally, they'll be Contents/MacOS/Kext but some have kexts hidden within under Plugin folder. Do note that plist only kexts do not need this filled in.

    • ex: Contents/MacOS/Lilu

  • PlistPath

    • Path to the info.plist hidden within the kext

    • ex: Contents/Info.plist

Emulate: Needed for spoofing unsupported CPUs like Pentiums and Celerons(AMD CPUs don't require this)

  • CpuidMask: Leave this blank

  • CpuidData: Leave this blank

Block: Blocks kexts from loading. Not relevant for us

Patch: Patches both the kernel and kexts

Quirks:

Settings relating to the kernel, for us we'll be enabling AppleCpuPmCfgLock, AppleXcpmCfgLock, DisableIOMapper, PanicNoKextDump, PowerTimeoutKernelPanic and XhciPortLimit. Everything else should be left as default

  • AppleCpuPmCfgLock: YES

    • Only needed when CFG-Lock can't be disabled in BIOS, Clover counterpart would be AppleIntelCPUPM. Please verify you can disable CFG-Lock, most systems won't boot with it on so requiring use of this quirk

  • AppleXcpmCfgLock: YES

    • Only needed when CFG-Lock can't be disabled in BIOS, Clover counterpart would be KernelPM. Please verify you can disable CFG-Lock, most systems won't boot with it on so requiring use of this quirk

  • AppleXcpmExtraMsrs: NO

    • Disables multiple MSR access needed for unsupported CPUs like Pentiums and many Xeons. Skylake-X can ignore

  • AppleXcpmForceBoost: NO

    • Forces maximum multiplier, only recommended to enable on scientific or media calculation machines that are constantly under load. Main Xeons benifit from this

  • CustomSMBIOSGuid: NO

    • Performs GUID patching for UpdateSMBIOSMode Custom mode. Usually relevant for Dell laptops

  • DisableIoMapper: YES

    • Needed to get around VT-D if either unable to disable in BIOS or needed for other operating systems, much better alternative to dart=0 as SIP can stay on in Catalina

  • DummyPowerManagement: NO

    • New alternative to NullCPUPowerManagement, required for all AMD CPU based systems as there's no native power management. Intel can ignore

  • ExternalDiskIcons: NO

    • External Icons Patch, for when internal drives are treated as external drives but can also make USB drives internal. For NVMe on Z87 and below you just add built-in property via DeviceProperties.

  • IncreasePciBarSize: NO

    • Increases 32-bit PCI bar size in IOPCIFamily from 1 to 4 GB, enabling Above4GDecoding in the BIOS is a much cleaner and safer approach. Some X99 boards may require this, you'll generally expereince a kernel panic on IOPCIFamily if you need this

  • LapicKernelPanic: NO

    • Disables kernel panic on AP core lapic interrupt, generally needed for HP systems. Clover equivalent is Kernel LAPIC

  • PanicNoKextDump: YES

    • Allows for reading kernel panics logs when kernel panics occur

  • PowerTimeoutKernelPanic: YES

    • Helps fix kernel panics relating to power changes with Apple drivers in macOS Catalina, most notably with digital audio.

  • ThirdPartyDrives: NO

    • Enables TRIM, not needed for NVMe but AHCI based drives may require this. Please check under system report to see if your drive supports TRIM

  • XhciPortLimit: YES

    • This is actually the 15 port limit patch, don't rely on it as it's not a guaranteed solution for fixing USB. Please create a USB map when possible.

The reason being is that UsbInjectAll reimplements builtin macOS functionality without proper current tuning. It is much cleaner to just describe your ports in a single plist-only kext, which will not waste runtime memory and such

Misc

Misc

Boot: Settings for boot screen (Leave everything as default)

  • HibernateMode: None

    • Best to avoid hibernation with Hackintoshes all together

  • HideSelf: YES

    • Hides the EFI partition as a boot option in OC's boot picker

  • PollAppleHotKeys: NO

    • Allows you to use Apple's hotkeys during boot, depending on the firmware you may need to use AppleUsbKbDxe.efi instead of OpenCore's builtin support. Do note that if you can select anything in OC's picker, disabling this option can help. Popular commands:

      • Cmd+V: Enables verbose

      • Cmd+Opt+P+R: Cleans NVRAM

      • Cmd+R: Boots Recovery partition

      • Cmd+S: Boot in Single-user mode

      • Option/Alt: Shows boot picker when ShowPicker set to NO, an alternative is ESC key

  • Timeout: 5

    • This sets how long OpenCore will wait until it automatically boots from the default selection

  • ShowPicker: YES

    • Shows OpenCore's UI, needed for seeing your available drives or set to NO to follow default option

  • TakeoffDelay: 0

    • Used to add a delay for hotkeys when OpenCore is a bit to fast to register, 5000-10000 microseconds is the prefered range for users with broken hotkeys support

  • UsePicker: YES

    • Uses OpenCore's default GUI, set to NO if you wish to use a different GUI

Debug: Helpful for debuggin OpenCore boot issues(We'll be chnging everything but DisplayDelay)

  • DisableWatchDog: YES (May need to be set for YES if OpenCore is stalling on something while booting, can also help for early macOS boot issues)

  • Target: 67

    • Shows more debug information, requires debug version of OpenCore

  • DisplayLevel: 2147483714

    • Shows even more debug information, requires debug version of OpenCore

These values are based of those calculated in OpenCore debugging

Security: Security is pretty self-explanatory, do not skip

We'll be changing AllowNvramReset, AllowSetDefault, RequireSignature, RequireVault and ScanPolicy

  • AllowNvramReset: YES

    • Allows for NVRAM reset both in the boot picker and when pressing Cmd+Opt+P+R

  • AllowSetDefault: YES

    • Allow CTRL+Enter and CTRL+Index to set default boot device in the picker

  • AuthRestart: NO:

    • Enables Authenticated restart for FileVault2 so password is not required on reboot. Can be concidered a security risk so optional

  • ExposeSensitiveData: 6

    • Shows more debug information, requires debug version of OpenCore

  • RequireSignature: NO

    • We won't be dealing vaulting so we can ignore, won't boot with this enabled

  • RequireVault: NO

    • We won't be dealing vaulting so we can ignore as well, won't boot with this enabled

  • ScanPolicy: 0

    • 0 allows you to see all drives available, please refer to Security section for further details. Will not boot USBs with this set to default

Tools Used for running OC debugging tools like the shell, ProperTree's snapshot function will add these for you. For us, we won't be using any tools

  • Name

    • Name shown in OpenCore

  • Enabled

    • Self-explanatory, enables or disables

  • Path

    • Path to file after the Tools folder

    • ex: Shell.efi

Entries: Used for specifying irregular boot paths that can't be found naturally with OpenCore

  • Name

    • Name shown in boot picker

  • Enabled

    • Self-explanatory, enables or disables

  • Path

    • PCI route of boot drive, can be found with the OpenCoreShell and the map command

    • ex: PciRoot(0x0)/Pci(0x1D,0x4)/Pci(0x0,0x0)/NVMe(0x1,09-63-E3-44-8B-44-1B-00)/HD(1,GPT,11F42760-7AB1-4DB5-924B-D12C52895FA9,0x28,0x64000)/\EFI\Microsoft\Boot\bootmgfw.efi

NVRAM

NVRAM

Add:

4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14 (Booter Path, mainly used for UI Scaling)

  • UIScale:

    • 01: Standard resolution(Clover equivalent is 0x28)

    • 02: HiDPI (generally required for FileVault to function correctly on smaller displays, Clover equivalent is 0x2A)

7C436110-AB2A-4BBB-A880-FE41995C9F82 (System Integrity Protection bitmask)

  • boot-args:

    • -v - this enables verbose mode, which shows all the behind-the-scenes text that scrolls by as you're booting instead of the Apple logo and progress bar. It's invaluable to any Hackintosher, as it gives you an inside look at the boot process, and can help you identify issues, problem kexts, etc.

    • debug=0x100- this disables macOS's watchdog which helps prevents a reboot on a kernel panic. That way you can hopefully glean some useful info and follow the breadcrumbs to get past the issues.

    • keepsyms=1 - this is a companion setting to debug=0x100 that tells the OS to also print the symbols on a kernel panic. That can give some more helpful insight as to what's causing the panic itself.

    • alcid=1 - used for setting layout-id for AppleALC, see supported codecs to figure out which layout to use for your specific system.

  • csr-active-config: Settings for SIP, generally recommended to manually change this within Recovery partition with csrutil via the recovery partition

csr-active-config is set to 00000000 which enables System Integrity Protection. You can choose a number of other options to enable/disable sections of SIP. Some common ones are as follows:

  • 00000000 - SIP completely enabled

  • 30000000 - Allow unsigned kexts and writing to protected fs locations

  • E7030000 - SIP completely disabled

Recommended to leave enabled for best security practices

  • nvda_drv: <>

    • For enabling Nvidia WebDrivers, set to 31 if running a Maxwell or Pascal GPU. This is the same as setting nvda_drv=1 but instead we translate it from text to hex, Clover equivalent is NvidiaWeb. AMD and Intel GPU users should leave this area blank.

  • prev-lang:kbd: <>

    • Needed for non-latin keyboards in the format of lang-COUNTRY:keyboard, recommeneded to keep blank though you can specify it(Default in Sample config is Russian):

    • American: en-US:0(656e2d55533a30 in HEX)

    • Full list can be found in AppleKeyboardLayouts.txt

Block: Forcibly rewrites NVRAM variables, do note that Add will not overwrite values already present in NVRAM so values like boot-args should be left alone.

LegacyEnable: NO

  • Allows for NVRAM to be stored on nvram.plist, needed for systems without native NVRAM

LegacyOverwrite: NO

  • Permits overwriting firmware variables from nvram.plist, only needed for systems without native NVRAM

LegacySchema

  • Used for assigning NVRAM variables, used with LegacyEnable set to YES

WriteFlash: YES

  • Enables writing to flash memory for all added variables.

Platforminfo

PlatformInfo

For setting up the SMBIOS info, we'll use CorpNewt's GenSMBIOS application.

For this Skylake example, we'll choose the iMac17,1 SMBIOS.

Run GenSMBIOS, pick option 1. for downloading MacSerial and Option 3. for selecting out SMBIOS. This will give us an output similar to the following:

#######################################################
# iMac17,1 SMBIOS Info #
#######################################################
Type: iMac17,1
Serial: C02S3HYWGG7L
Board Serial: C02629102GUGPF7AD
SmUUID: 3508AD44-B67D-4AD7-A109-7955130A1033

The Type part gets copied to Generic -> SystemProductName.

The Serial part gets copied to Generic -> SystemSerialNumber.

The Board Serial part gets copied to Generic -> MLB.

The SmUUID part gets copied toto Generic -> SystemUUID.

We set Generic -> ROM to either an Apple ROM (dumped from a real Mac), your NIC MAC address, or any random MAC address (could be just 6 random bytes, for this guide we'll use 11223300 0000. After install follow the Fixing iServices page on how to find your real MAC Address)

Reminder that you want either an invalid serial or valid serial numbers but those not in use, you want to get a message back like: "Invalid Serial" or "Purchase Date not Validated"

Apple Check Coverage page

Automatic: YES

  • Generates Platforminfo based on Generic section instead of DataHub, NVRAM, and SMBIOS sections

Generic:

  • SpoofVendor: YES

    • Swaps vendor field for Acidanthera, generally not safe to use Apple as a vendor in most case

  • SupportsCsm: NO

    • Used for when the EFI partition isn't first on the windows drive

      UpdateDataHub: YES

  • Update Data Hub fields

UpdateNVRAM: YES

  • Update NVRAM fields

UpdateSMBIOS: YES

  • Updates SMBIOS fields

UpdateSMBIOSMode: Create

  • Replace the tables with newly allocated EfiReservedMemoryType, use Custom on Dell laptops requiring CustomSMBIOSGuid quirk

UEFI

UEFI

ConnectDrivers: YES

  • Forces .efi drivers, change to NO will automatically connect added UEFI drivers. This can make booting slightly faster, but not all drivers connect themselves. E.g. certain file system drivers may not load.

Drivers: Add your .efi drivers here

Input: Related to boot.efi keyboard passthrough used for FileVault and Hotkey support, everything should be left as default

  • KeyForgetThreshold: 5

    • The delay between each key input when holding a key down, for best results use 5 milliseconds

  • KeyMergeThreshold: 2

    • The length of time that a key will be registered before resetting, for best results use 2 milliseconds

  • KeySupport: YES

    • Enables OpenCore's built in key support and required for boot picker selection, do not use with AppleUsbKbDxe.efi

  • KeySupportMode: Auto

    • Keyboard translation for OpenCore

  • KeySwap: NO

    • Swaps Option and Cmd key

  • PointerSupport: NO

    • Used for fixing broken pointer support, commonly used for Z87 Asus boards

  • PointerSupportMode: [Blank]

    • Specifies OEM protocol, currently only supports Z87 and Z97 ASUS boards so leave blank

  • TimerResolution: 50000

    • Set architecture timer resolution, Asus Z87 boards use 60000 for the interface. Settings to 0 can also work for some

Protocols: (Most values can be ignored here as they're meant for real Macs/VMs, the one we care about is ConsoleControl)

  • AppleSmcIo: NO

    • Reinstalls Apple SMC I/O, this is the equivlant of VirtualSMC.efi which is only needed for users using FileVault

  • ConsoleControl: YES

    • Replaces Console Control protocol with a builtin version, set to YES otherwise you may see text output during booting instead of nice Apple logo. Required for most APTIO firmware

  • FirmwareVolume: NO

    • Fixes UI regarding Filevault, set to YES for better FileVault compatibility

  • HashServices: NO

    • Fixes incorrect cursor size when running FileVault, set to YES for better FileVault compatibility

  • UnicodeCollation: NO

    • Some older firmware have broken Unicode collation, fixes UEFI shell compatibility on these systems(generally IvyBridge and older)

Quirks:

Settings relating to UEFI, main ones we need to change: ProvideConsoleGop, and RequestBootVarFallback

  • AvoidHighAlloc: NO

    • Workaround for when te motherboard can't properly access higher memory in UEFI Boot Services. Avoid unless necessary(affected models: GA-Z77P-D3 (rev. 1.1))

  • ExitBootServicesDelay: 0

    • Only required for very specific use cases like setting to 5 for ASUS Z87-Pro running FileVault2

  • IgnoreInvalidFlexRatio: NO

    • Fix for when MSR_FLEX_RATIO (0x194) can't be disabled in the BIOS, required for all pre-skylake based systems

  • IgnoreTextInGraphics: NO

    • Fix for UI corruption when both text and graphics outputs happen, set to YES with SanitiseClearScreen also set to YES for pure Apple Logo(no verbose screen)

  • ProvideConsoleGop: YES

    • Enables GOP(Graphics output Protcol) which the macOS bootloader requires for console handle, required for seeing once the kernel takes over

  • ReleaseUsbOwnership: NO

    • Releases USB controller from firmware driver, needed for when your firmware doesn't support EHCI/XHCI Handoff. Clover equivalent is FixOwnership

  • RequestBootVarFallback: YES

    • Request fallback of some Boot prefixed variables from OC_VENDOR_VARIABLE_GUID to EFI_GLOBAL_VARIABLE_GUID. Used for fixing boot options.

  • RequestBootVarRouting: YES

    • Redirects AptioMemeoryFix from EFI_GLOBAL_VARIABLE_GUID to OC\_VENDOR\_VARIABLE\_GUID. Needed for when firmware tries to delete boot entries and is recommended to be enabled on all systems for correct update installation, Startup Disk control panel functioning, etc.

  • ReplaceTabWithSpace: NO

    • Depending on the firmware, some system may need this to properly edit files in the UEFI shell when unable to handle Tabs. This swaps it for spaces instead-but majority can ignore it but do note that ConsoleControl set to True may be needed

  • SanitiseClearScreen: NO

    • Fixes High resolutions displays that display OpenCore in 1024x768, recommended for users with 1080P+ displays

  • ClearScreenOnModeSwitch: NO

    • Needed for when half of the previously drawn image remains, will force black screen before switching to TextMode. Do note that ConsoleControl set to True may be needed

  • UnblockFsConnect: NO

    • Some firmware block partition handles by opening them in By Driver mode, which results in File System protocols being unable to install. Mainly relevant for HP systems when no drives are listed

Cleaning up

And now you're ready to save and place it into your EFI under EFI/OC.

For those having booting issues, please make sure to read the Troubleshooting section first and if your questions are still unanswered we have plenty of resources at your disposal:

Intel BIOS settings

Disable:

  • Fast Boot

  • VT-d(can be enabled if you set DisableIoMapper to YES)

  • CSM

  • Thunderbolt

  • Intel SGX

  • Intel Platform Trust

  • CFG Lock(MSR 0xE2 write protection)(This must be off, if you can't find the option then enable both AppleCpuPmCfgLock and AppleXcpmCfgLock under Kernel -> Quirks. Your hack will not boot with CFG-Lock enabled)

Enable:

  • VT-x

  • Above 4G decoding

  • Hyper-Threading

  • Execute Disable Bit

  • EHCI/XHCI Hand-off

  • OS type: Windows 8.1/10 UEFI Mode

Post-install

So what in the world needs to be done once everything is installed? Well here's some things you can do: