Re: [Xen-devel] [Minios-devel] [PATCH 1/2] mini-os: support keeping start_info structure conditionally

[Juergen Gross <jgross@xxxxxxxx>]

On 29/08/16 13:09, Wei Liu wrote:
> On Mon, Aug 29, 2016 at 01:01:08PM +0200, Juergen Gross wrote:
>> grub stubdom needs the start_info structure. Keep a copy of it in
>> pv mini-os if configured via "CONFIG_KEEP_STARTINFO". This should
>> default to "n" in order to have it enabled only when really needed.
>>
> 
> I'm not sure I understand the rationale for this.
> 
> Shouldn't start_info always be kept when mini-os is PV? Under what
> condition should it not be kept?

The application on top of Mini-OS shouldn't depend on Mini-OS being
paravirtualized or not in the "normal" case. grub-stubdom is a
special case, as it needs to kexec to a loaded kernel which in turn
needs the start_info, of course.

ioemu-stubdom OTOH should not need start_info as it could work on
a HVMlite Mini-OS, too.

The idea of removing start_info in my HVMlite series was driven by
that thought: any application using start_info should break as it
clearly wouldn't be agnostic of the mode (pv or HVMlite) of Mini-OS.
pv-grub was an oversight here.

I'm planning to modify ioemu-stubdom in the future to not use
start_info and then let it run in HVMlite mode, too.


Juergen


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