Re: [Qemu-devel] [RFC PATCH 00/14] Implement network booting directly into the s390-ccw BIOS

[Thomas Huth]

On 28.06.2017 10:02, Thomas Huth wrote:
> On 28.06.2017 09:28, Viktor Mihajlovski wrote:
>> On 27.06.2017 23:40, Thomas Huth wrote:
>> [...]
>>>>> - Is it OK to require loading an .INS file first? Or does anybody
>>>>>   have a better idea how to load multiple files (kernel, initrd,
>>>>>   etc. ...)?
>>>> It would be nice to support PXE-style boot, because the majority of boot
>>>> servers is set up that way. A straightforward way would be to do a PXE
>>>> emulation by attempting to download a pxelinux.cfg from the well-known
>>>> locations, parsing the content (menu) and finally load the kernel,
>>>> initrd and set the kernel command line as specified there. (I know, but
>>>> you're already parsing the INS-File).
>>>
>>> Please, don't mix up PXE and pxelinux (since you've used both terms in
>>> above paragraph). Assuming that you're only talking about pxlinux config
>>> files... are they that common on s390x already? Using the pxelinux
>>> config file syntax sounds like we would be completely bound to only
>>> loading Linux guests to me, since the boot loader has to know where to
>>> load the initrd and how to patch the kernel so that it can find the initrd.
>>> Using .INS files sounds more flexible to me instead, since you can also
>>> specify the addresses here - so you can theoretically also load other
>>> guest kernels, and that's IMHO the better approach since a firmware
>>> should stay as generic as possible.
>>>
>> In order to be consumable, the network boot should support the most
>> common configurations. I would think that most network boot servers are
>> setup as PXE boot servers using pxelinux configs.
> 
> Are you really sure about the popularity of pxelinux? It's just one
> flavor of secondary stage network boot loaders - which also only exist
> on x86 so far, as far as I know.

And it seems like it also only works with legacy BIOSes, i.e. you can
not use it on EFI-only systems, if I've got that right:

https://github.com/openSUSE/kiwi/wiki/Setup-PXE-boot-with-EFI-Using-GRUB2

So I guess the significance of pxelinux will very likely decrease in
the next years...

 Thomas