Re: [PATCH 00/31 v2] PTI support for x86_32

[Greg KH]

On Sun, Feb 11, 2018 at 09:40:41AM -0800, Mark D Rustad wrote:
> > On Feb 11, 2018, at 2:59 AM, Adam Borowski <kilobyte@xxxxxxxxxx> wrote:
> > 
> >> Does Debian make it easy to upgrade to a 64-bit kernel if you have a
> >> 32-bit install?
> > 
> > Quite easy, yeah.  Crossgrading userspace is not for the faint of the heart,
> > but changing just the kernel is fine.
> 
> ISTR that iscsi doesn't work when running a 64-bit kernel with a
> 32-bit userspace. I remember someone offered kernel patches to fix it,
> but I think they were rejected. I haven't messed with that stuff in
> many years, so perhaps the userspace side now has accommodation for
> it. It might be something to check on.

IPSEC doesn't work with a 64bit kernel and 32bit userspace right now.

Back in 2015 someone started to work on that, and properly marked that
the kernel could not handle this with commit 74005991b78a ("xfrm: Do not
parse 32bits compiled xfrm netlink msg on 64bits host")

This is starting to be hit by some Android systems that are moving
(yeah, slowly) to 4.4 :(

thanks,

greg k-h