Darwin boot loader level flags, for Darwin version 8.0:-

• -v = verbose mode. Basically tells you wants happening during boot up.System in Verbose mode display a lot of log lines during boot time and does not display the apple gray boot screen, it is good to use this option if things go wrong, or if you get an error screen and you want to know the reason.

• -x = Safe mode. Basically boots your system with the bare minimum kexts. This option boot the system into safe mode ignoring kext cache and loads only necessary kext

•  -s = Single user mode. Command line only mode. Allows you to run commands as root to fix system.This mean you would like to enter “Single User” mode which doesn’t load GUI and doesn’t mount partitions but gives you a prompt so you can make system maintenance and recovery procedures.

•  -f = Tells the hackintosh to reload all kext (Kernel Extensions = drivers) and dump the cache, not rely on it (kext cache found in: /System/Library/Extensions.mkext, you can delete it manually and the system will recreate it)
• cpus= this parameter tells the hackintosh how many cpus to use, for instance if you have dual CPU or dual Core then you can state cpus=2, so the system will use both cpus, and if you get reboot without loading GUI or boot screen then you may use cpus=1 to allow use of one cpu and avoid reboot

• “Graphics Mode” = this parameter tells the hackintosh to use stated graphics resolution and color depth, the pattern to use is: WidthxHeightxDepth@RefreshRate for instance a resolution of 1024×768 with 32 bit color depth and 60 hertz frequancy refresh rate will look like this:

“Graphics Mode”=1024x768x32@60

• config= this parameter tells the system to load using different copy of the boot config file, the default copy used is kept in:

/Library/Preferences/SystemConfiguration/com.apple.Boot.plist

The content of this file state boot options such as:

1. timeout (how much time to wait for user selection in boot prompt)
2. Kernel (what kernel to use)
3. Kernel flags (what kernel flags to use in each and every boot)
4. Quiet boot (weather to display boot menu or not)
5. Boot graphics (if to boot with apple spinning circle)

ACPI Flags are as on :

• acpi=off = Don’t enable ACPI
  
• acpi=ht = Use ACPI boot table parsing, but don’t enable ACPI interpreter
  
• acpi=force = Force ACPI on (currently not needed)
  
• acpi=strict = Disable out of spec ACPI workarounds.
  
• acpi_sci = {edge,level,high,low} Set up ACPI SCI interrupt. EX:
  
• acpi_sci = edgeacpi=noirq = Don’t route interrupts

Single user mode is a mode in which a multiuser computer operating system boots into a single superuser. It is mainly used for maintenance of multi-user environments such as network servers. Some tasks may require exclusive access to shared resources, for example running fsck on a network share.You can use key combinations to start up the computer in either single-user mode or verbose mode. These may be used for troubleshooting or software development. "Single User" is a boot

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Procedure to enter in Single User Mode.
* Restart your computer
* Continuously press F8 until you see the Darwin boot prompt
* write "-s" without the quotation marks and press you will soon reach a prompt
To exit single-user mode type reboot  then press Return.

Procedure to enter in Verbose Mode.

* Restart your computer

* Continuously press F8 until you see the Darwin boot prompt

* write "-V" without the quotation marks and press you will soon reach a prompt

Verbose mode exits automatically when the computer’s startup process progresses sufficiently and the blue screen appears

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