Re: [Qemu-devel] [PATCH] vl.c: disallow command line fw cfg without opt/

[Corey Minyard <cminyard@mvista.com>]

On 03/15/2016 09:58 AM, Michael S. Tsirkin wrote:
> On Tue, Mar 15, 2016 at 03:54:36PM +0100, Paolo Bonzini wrote:
>>
>> On 15/03/2016 15:25, Michael S. Tsirkin wrote:
>>> Do you look at all warnings all your software prints?
>> Yes.  I also try to understand them, and if they seem useless I propose
>> a patch upstream.
>>
>>> What if user uses some tool to build the command line?
>>>
>>> consider mem-path - for years we printed a warning if
>>> it's not on hugetlbfs. It worked and users just ignored it.
>> That was a bad warning though.  There was no reason to warn.
>>
>> It was also the smallest problem with the original hugetlbfs patches.
>>
>>> So now Corey basically is prevented from sorting sanely
>>> because command line might not start with opt/
>> Can you explain?
>>
>> Paolo
> Ask Corey:
> http://thread.gmane.org/gmane.comp.emulators.qemu/400540/focus=400799
>
>
I think what Paulo is saying is that if you don't use /opt, then all bets
are off whether it works properly.  You were warned and ignored it.

I can go either way with this, you can enforce it (which seems like
the safer route to me) or you can just say that it may not work right
if you don't use /opt.

With the new patch I just posted it won't actually make any difference.
It doesn't look at file names for some things, that ended up not working
because in at least one situation the same file name would end up
in different places depending on the situation, and the order of some
things vary depending on the order the user lists them.

(The one I found was that if you have a pc-0.11 or earlier, if you have
a PCI VGA card it ends up adding a fw_cfg item for the ROM when
VGA is initialized.  If you have an ISA VGA card, it will have the same
file name but will end up where device initialization occurs.)

The solution I ended up with was a fixed specified order, but in
certain sections (VGA, NIC, user added, and devices) they will be
ordered by when they were inserted.

-corey