[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [virt-tools-list] How do the bootloader and kernel image both get transferred to the VM in the "Network install" option?



On Tue, Sep 11, 2012 at 04:45:18PM +0100, Richard W.M. Jones wrote:

> On emulated PC-like architectures ...
> 
> virt-install downloads the kernel and initrd.  It knows where to
> download them relative to the URL you give it via a set of hard-coded
> rules.  libvirt invokes KVM with the -kernel and -initrd options.
> 
> KVM then presents these files through a simple virtual hardware
> interface called fwcfg (firmware config).  (fwcfg isn't really
> documented, but someone did "reverse engineer" it from the sources the
> other day -- unfortunately I cannot find that link right now).
> 
> The BIOS (SeaBIOS) knows how to query the fwcfg interface and load the
> files and the kernel command line at a predefined memory location.  It
> jumps to the kernel which finds the location of initrd (and the
> command line?) via the multiboot spec.
> 
> It all works in different ways on other architectures.

Thanks Richard for this thorough explanation.
		
	Marwan


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]