- Where is the kernel in mac disk image drivers#
- Where is the kernel in mac disk image software#
- Where is the kernel in mac disk image code#
Bootloader is stored on the ROM on the motherboard. Bootloader or bootstrap loader is stored in Read-only-Memory (ROM), EPROM or Flash memory. Bootloader is a program that loads the kernel into RAM when the compter is started. How does the OS start? What is BootloaderWhen OS is installed, it is stored on the hard disk, a non-volatile memory. Kernel also has an interface to handle system calls from user layer.
Where is the kernel in mac disk image code#
Kernel has code which is unique to the hardware platform and code common to all platforms. Kernel space is part of the RAM where the Kernel is loaded. User mode has applications or tools which in turn interact with Kernel directly or indirectly via system libraries, device drivers.
Where is the kernel in mac disk image drivers#
Device drivers are softwares that interact (take input or provide output or both) with the firmware of the particular device.
Where is the kernel in mac disk image software#
System libraries help Software applications to pass instructions to the Kernel or the Device drivers. There are other system libraries and device drivers. Linux has a monolithic Kernel layer which interacts with the hardware. In that case, diskarbitrationd shouldn't notice it, and you will need to call mount() explicitly from your daemon.Operating System Kernel Architecture and Features - Windows, Linux and MacOSĪrchitecture of Linux OSLinux architecture has kernel mode and user mode. You can probably also bypass the IOStorage stack entirely and only create the BSD dev node in your kext. But this also lets you influence mounting of disk images handled by diskimages-helper, so if you are using an image format supported by it, you won't need to write your own and can simply intercept the mounting and do whatever it is you want to do yourself. The second part, mounting, is done by diskarbitrationd automatically if you are using the IOStorage stack, but you can influence it via a disk arbitration dissenter. You can probably get away with implementing it entirely in-kernel if you prefer, although it's probably not a great idea. So if you want to implement your own disk image format, you'll need to recreate something similar to Apple's diskimage-helper and IOHDIXController.kext. The HDIX subsystem is not open as far as I'm aware. This then causes device discovery events to fire in diskarbitrationd, which moves on to the second part of the process: calling mount(2) on the newly discovered IOMedia objects' /dev/diskXsY node(s) as appropriate. This appears to the OS like a physical block device, and the usual stack of IOBlockStorageDriver -> IOMedia -> IOPartitionScheme -> IOMedia -> IOMediaBSDClient objects configures itself on top of it. dmg file or similar, the diskimages-helper daemon opens & parses it and instructs the IOHDIXController to create a new IODiskImageBlockStorageDeviceOutKernel instance (an IOBlockStorageDevice subclass). They're implemented in the IOHDIXController object (code for this is in a kext), which you'll find attached to IOResources in the IORegistry. Mounting a file system on a block device.ĭisk image support is not an intrinsic part of the xnu kernel.Opening disk images and creating a virtual block device for accessing their contents.I think you might be conflating 2 concepts here, which are actually entirely separate: In user space however, there's a lot more than amework at your disposal: there's the amework, and of course the POSIX syscall of mount(2). There isn't a public KPI for initiating a mount, and I'm not even aware of a function in.