Re: [PATCH] lib/ubsan: default UBSAN_ALIGNMENT to not set

[Andrew Morton]

On Fri, 11 Jan 2019 22:01:16 +0300 Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote:

> 
> 
> On 12/17/18 6:03 PM, Anders Roxell wrote:
> > When booting an allmodconfig kernel, there are a lot of false-positives.
> > With a message like this 'UBSAN: Undefined behaviour in...' with a call
> > trace that follows.
> > 
> > Reworked so that when building a allmodconfig kernel that turns
> > everything into '=m' or '=y' will turn off UBSAN_ALIGNMENT.
> > 
> > Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
> > Signed-off-by: Anders Roxell <anders.roxell@xxxxxxxxxx>
> > ---
> 
> Acked-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
> 

Confused.  Why does allmodconfig result in UBSAN warnings?