Re: Booting uncompressed kernel images
Ian,
On 2 February 2016 at 15:32, Ian Campbell <ijc@debian.org> wrote:
> Yes, although I think/suspect that my 47B4 is created by binwalk
> decompressing 47B4.xz as a convenience.
>
> (...)
>
> This looks like a file which I would expect to be bootable as a Xen PV
> guest. Using "readelf -n" should show lots of:
>
> Displaying notes found at file offset 0x00716774 with length 0x000001d8:
> Owner Data size Description
> Xen 0x00000006 Unknown note type: (0x00000006)
>
> Which would imply this.
>
> (...)
>
> It depends ;-).
>
> Grub2 can support many different platforms, including "native PC" and "Xen
> PV". http://wiki.xen.org/wiki/PvGrub2#Background:_Introduction_to_Xen_PV_Bo
> otloaders has some background which I hope will be useful here (the second
> part on actually using grub2 is not really relevant since you are at the
> mercy of Oracle Cloud).
>
> "Xen HVM" == "native PC" from a booting point of view, so in a Xen HVM
> guest you would use the native grub, in a Xen PV guest it's possible that
> you are using the "Xen PV" version of Grub2.
>
> A native version of Grub will not be able to boot the raw ELF file
> extracting from the vmlinuz, but it should be able to boot the vmlinuz
> itself just fine.
>
> Virtual box == "native PC" too, I think it unlikely it would be able to
> boot a raw ELF file.
>
> (...)
>
> Do you need the custom kernel on your local install?
>
> Having grub2 installed in a PV guest does not necessarily mean it is being
> used, since the first stage bootloader is provided by the host. The package
> supporting Xen PV is "grub-xen"
>
> If you are booting PV grub2 then perhaps you just need to add "insmod xzio"
> to your grub.cfg?
>
> (...)
>
> I think you should ignore VirtualBox for the purposes of diagnosing what is
> going on here, behaviour on VB tells us next to nothing about behaviour on
> Xen.
>
> (...)
>
> You really need to figure out for sure if you are booting in an HVM or PV
> guest, it makes a very large difference to what kernel features you
> want/need. From there it should become pretty clear what bootloader is in
> use.
>
> If you can boot the guest in some way then virt-what ought to tell you for pretty sure what you are running in.
Sorry for the delay in my response. In the past couple days I was
confirming with Oracle if my findings (using virt-what, as you
suggested) where right and, indeed, they are supporting Xen HVM right
now.
So, there's no need for an uncompressed/gzipped kernel anymore and the
default one boots just fine. Although I'm still curious regarding the
possibility of booting an uncompressed kernel on
native/full-virtualization, I guess this does not makes sense.
I'm really thankful for you support and inclination to help us on the matter.
Very best regards,
Tiago.
--
Tiago "Myhro" Ilieve
Blog: https://blog.myhro.info/
GitHub: https://github.com/myhro
LinkedIn: https://br.linkedin.com/in/myhro
Montes Claros - MG, Brasil
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