[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Discussion: xen hvm guest direct kernel boot
On Fri, Apr 25, 2014 at 01:08:18AM -0600, Chun Yan Liu wrote: > Hi, > Hello, > I'm looking at xen hvm guest direct kernel boot and interested to do > it. I found there were some discussions about it and an early work > around by Daniel (based on xen qemu-dm). > [1]http://old-list-archives.xenproject.org/xen-devel/2011-08/msg00414.html > [2]http://old-list-archives.xenproject.org/archives/html/xen-devel/2007-12/msg00723.html > > In xen, the BIOS is provided by hvmloader, which is loaded to RAM in > libxc. When hvmloader finishes, it jumps to BIOS entry point. BIOS > will probe for MBR from qemu disk, through grub loading kernel and > initrd to correct address and then start the guest kernel. > > In [2], the work around implementation is to pass kernel and initrd > to qemu, qemu reads kernel and initrd to certain address and generate > a boot sector on the 1st disk for BIOS probing. > > But in current qemu code, the load_linux() way is different. It reads > kernel and initrd to certain address, then put linuxboot.bin and > multiboot.bin to option roms which will intercept boot process, so > that boot process will jump to linuxboot.bin/multiboot.bin instead > of normal int19 probing MBR stage. This sounds much cleaner then > generating a boot sector. And in current xen hvmloader, it uses > seabios, which is also the one upstream qemu uses. > > So, back to xen direct kernel boot, I wonder if not generate a boot > sector for BIOS probing, could we break hvmloader limitation and > borrow qemu load_linux() way to achieve the goal? Then, where is the > right place to load the kernel and initrd, any way to intercept boot > process? Could we touch hvmloader? > > My knowledge is limited in this part. Welcome experts' clues or ideas > or discussions. Thanks. > I'm not an expert on this feature, but it sounds like an useful feature to have, for easier testing of guest kernels etc. Konrad maybe has some comments/ideas as Xen 4.5 release coordinator. -- Pasi > Regards, > Chunyan > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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