From: Segher Boessenkool <segher@kernel.crashing.org>
To: David Laight <David.Laight@ACULAB.COM>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"kbuild-all@lists.01.org" <kbuild-all@lists.01.org>,
"lkp@intel.com" <lkp@intel.com>,
"robh@kernel.org" <robh@kernel.org>,
Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
"bauerman@linux.ibm.com" <bauerman@linux.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
"dan.carpenter@oracle.com" <dan.carpenter@oracle.com>,
'Daniel Axtens' <dja@axtens.net>
Subject: Re: [PATCH] powerpc: Initialize local variable fdt to NULL in elf64_load()
Date: Thu, 22 Apr 2021 11:54:37 -0500 [thread overview]
Message-ID: <20210422165437.GA27473@gate.crashing.org> (raw)
In-Reply-To: <3e6b31d92d5042d982daeb989e49299e@AcuMS.aculab.com>
On Thu, Apr 22, 2021 at 08:05:27AM +0000, David Laight wrote:
> > (Does anyone - and by anyone I mean any large distro - compile with
> > local variables inited by the compiler?)
>
> There are compilers that initialise locals to zero for 'debug' builds
> and leave the 'random' for optimised 'release' builds.
> Lets not test what we are releasing!
Yeah, that's the worst of all possible worlds.
> I also think there is a new option to gcc (or clang?) to initialise
> on-stack structures and arrays to ensure garbage isn't passed.
> That seems to be a horrid performance hit!
> Especially in userspace where large stack allocations are almost free.
>
> Any auto-initialise ought to be with a semi-random value
> (especially not zero) so that it is never right and doesn't
> lead to lazy coding.
Many compilers did something like this, decades ago -- for debug builds.
Segher
next prev parent reply other threads:[~2021-04-22 16:58 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210415191437.20212-1-nramas@linux.microsoft.com>
2021-04-15 19:18 ` [PATCH] powerpc: Initialize local variable fdt to NULL in elf64_load() Lakshmi Ramasubramanian
2021-04-16 6:44 ` Daniel Axtens
2021-04-16 7:00 ` Christophe Leroy
2021-04-16 8:09 ` Dan Carpenter
2021-04-16 12:19 ` Michael Ellerman
2021-04-16 7:40 ` Dan Carpenter
2021-04-16 9:05 ` Michael Ellerman
2021-04-16 14:37 ` Lakshmi Ramasubramanian
2021-04-19 23:30 ` Michael Ellerman
2021-04-20 1:33 ` Lakshmi Ramasubramanian
2021-04-20 5:00 ` Dan Carpenter
2021-04-20 5:20 ` Lakshmi Ramasubramanian
2021-04-20 13:06 ` Rob Herring
2021-04-20 14:42 ` Lakshmi Ramasubramanian
2021-04-20 15:04 ` Lakshmi Ramasubramanian
2021-04-20 15:47 ` Rob Herring
2021-04-20 15:55 ` Lakshmi Ramasubramanian
2021-04-22 2:21 ` Daniel Axtens
2021-04-22 8:05 ` David Laight
2021-04-22 9:34 ` Dan Carpenter
2021-04-22 16:54 ` Segher Boessenkool [this message]
2021-04-23 13:50 ` Michael Ellerman
2021-04-23 14:42 ` David Laight
2021-04-23 15:11 ` Rob Herring
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