Re: [Xen-devel] [PATCH 3/5] libxc: create unmapped initrd in domain builder if supported

[Juergen Gross <jgross@xxxxxxxx>]

On 09/11/2015 03:15 PM, Julien Grall wrote:
> On 11/09/15 13:54, Ian Jackson wrote:
> > Juergen Gross writes ("[PATCH 3/5] libxc: create unmapped initrd in domain builder 
> > if supported"):
> > > In case the kernel of a new pv-domU indicates it is supporting an
> > > unmapped initrd, don't waste precious virtual space for the initrd,
> > > but allocate only guest physical memory for it.
> > ...
> >
> > The name of this ELFNOTE suggests that it applies to all multiboot
> > modules, not just ramdisks.  In particular, that means perhaps it
> > ought to apply to device tree blobs too ?
> The device tree blobs is not a multiboot module but directly pass in a
> register to the kernel.
>
> FWIW, we don't have any ELF support right now on ARM.
Okay, I thought so, but I wasn't sure.

> > > -    /* load ramdisk */
> > > -    if ( dom->ramdisk_blob )
> > > +    /* Load ramdisk if initial mapping required. */
> > > +    if ( dom->ramdisk_blob &&
> > > +         (!dom->parms.elf_notes[XEN_ELFNOTE_MOD_START_PFN].data.num ||
> > > +          dom->ramdisk_seg.vstart) )
> > After this patch the resulting structure of the code is rather
> > unfortunate, in that the order of the main processing steps depends on
> > this ELFNOTE.
> Shouldn't we ought to have a common code ELF agnostic? I.e we may have
> other kernel image format where we have notes but not ELF notes.
dom->parms is the same for all architectures. I think it would have to
be extended in that case.


Juergen

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