From: Adam Borowski <kilobyte@angband.pl>
To: Jan Engelhardt <jengelh@inai.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Naresh Kamboju <naresh.kamboju@linaro.org>,
open list <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
lkft-triage@lists.linaro.org, Borislav Petkov <bp@suse.de>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@kernel.org>
Subject: Re: RETBleed: WARNING: Spectre v2 mitigation leaves CPU vulnerable to RETBleed attacks, data leaks possible!
Date: Sun, 24 Jul 2022 14:30:28 +0200 [thread overview]
Message-ID: <Yt07ZMAT+EEHvt/M@angband.pl> (raw)
In-Reply-To: <3139s0q2-2o3s-4334-o670-n3p223o34ps9@vanv.qr>
On Sun, Jul 24, 2022 at 11:25:04AM +0200, Jan Engelhardt wrote:
> On Saturday 2022-07-23 23:50, Adam Borowski wrote:
> >> > We are booting the i386 kernel on an x86 machine.
> >
> >[..] And for quite some tasks, halved word
> >size (thus ~2/3 memory usage) can overcome register starvation and win
> >benchmarks.
>
> So how many benchmarks does a 32-bit userspace with a 32-bit kernel
> win over 32-bit userspace with a 64-bit kernel?
Likely none or almost none.
What we want is for people to run 64-bit kernel, there are no real issues
with userland.
Valid uses to run 32-bit kernel:
* ancient hardware (so much more prevalent than m68k we support!;
non-hobbyists should upgrade to reduce power costs)
* hardware to run that 100$k-1M ISA industrial control/medical imaging card
(which, having ISA, is necessarily ancient too)
* us devs testing the above
Only the last case will have a modern CPU, thus requiring an explicit
override won't hurt less educated users -- while telling the latter to grab
a 64-bit kernel if their hardware isn't ancient would have other benefits
for them beside just vulnerabilities.
Meow!
--
⢀⣴⠾⠻⢶⣦⠀ Aryans: split from other Indo-Europeans ~2900-2000BC → Ural →
⣾⠁⢠⠒⠀⣿⡁ Bactria → settled 2000-1000BC in northwest India.
⢿⡄⠘⠷⠚⠋⠀ Gypsies: came ~1000AD from northern India; aryan.
⠈⠳⣄⠀⠀⠀⠀ Germans: IE people who came ~2800BC to Scandinavia; not aryan.
prev parent reply other threads:[~2022-07-24 12:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-14 8:45 RETBleed: WARNING: Spectre v2 mitigation leaves CPU vulnerable to RETBleed attacks, data leaks possible! Naresh Kamboju
2022-07-14 9:01 ` Greg Kroah-Hartman
2022-07-14 9:40 ` Peter Zijlstra
2022-07-15 22:19 ` Pawan Gupta
2022-07-23 21:50 ` Adam Borowski
2022-07-24 9:25 ` Jan Engelhardt
2022-07-24 12:30 ` Adam Borowski [this message]
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