[kpatch] Stacking patches which introduce new data

[Josh Poimboeuf]

On Tue, Sep 20, 2016 at 02:05:36PM +0100, Ross Lagerwall wrote:
> Hi,
> 
> The recommended way of applying multiple patches is to apply cumulative
> patches on top of the existing ones [1].
> 
> If the first patch introduces some new static/global data, the second patch,
> being cumulative, will define the same new static/global data. When the
> second patch is loaded, it will use its own copy of the new data which may
> not contain the same values as the existing data from patch 1.
> 
> Has this problem been considered at all? Are there any known solutions?
> 
> [1] https://www.redhat.com/archives/kpatch/2015-November/msg00001.html

Hi Ross,

Hm, I don't think we've ever considered this issue.  At least in my
experience, I've never needed to add a global variable which needed to
keep its value across a cumulative update.

Is this more of a theoretical question, or did you encounter this issue
with a real patch?

-- 
Josh