Re: [PATCH] docs/designs: re-work the xenstore migration document...

[Julien Grall <julien@xxxxxxx>]

Hi,

On 24/04/2020 16:59, Jürgen Groß wrote:
> On 24.04.20 17:44, Julien Grall wrote:
> If I extend the record and do a downgrade I'm losing the information,
> too, as the old version won't read it in any case. BTW, extending the
> record is no problem, as the length is stored in the header. Unknown
> records (and extensions) will be just ignored when reading.
That's very much up to the implementation. An implementation may decide 
to bail out if the record is not an exact size.
> In your case when reusing the paddings and doing a downgrade you would
> crash, as the paddings are no longer zero.
>
> In case a downgrade should not be done due to vital information loss
> then you should just not do it.
Of course, however I don't think a user will necessarily know it should 
not do it. So how do you protect against misuse?
Cheers,

--
Julien Grall