Re: [Qemu-devel] Slow kernel/initrd loading via fw_cfg; Was Re: Hack integrating SeaBios / LinuxBoot option rom with QEMU trace backends

[Lluís Vilanova]

Richard W M Jones writes:

> On Sat, Oct 15, 2011 at 10:00:02AM +0000, Blue Swirl wrote:
>> I don't understand why PC can't use the same way of loading initrd by
>> QEMU to guest memory before boot as Sparc32 uses. It should even be
>> possible to deduplicate the kernel and initrd images: improve the
>> loader to use mmap() for loading so that several guests would use the
>> same pages. Preloaded kernel and initrd are paravirtual anyway, there
>> could be even guest visible changes if ever needed (e.g. map
>> kernel/initrd pages outside of normal RAM areas).

> +1!

> Even better if we extended Linux so it worked more like OS-9 (circa
> 1990): At boot, scan memory for modules and insmod them.  That way we
> wouldn't even need an initrd since we could just supply the correct
> list of modules that the guest needs to mount its root disk.

I'm not really knowledgeable of the topic at hand, but if the objective is to
boot the kernel image given through QEMU's cmdline, QEMU can just put the files
in memory in a way that is compliant to what grub already does, which is a
format well understood by linux itself (multiboot modules, I think they're
called).


Lluis

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