linux-kernel - stop breaking dosemu (Re: x86/kconfig/32: Rename CONFIG

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Message-ID: <55E6C36F.6080309@list.ru>
Date:	Wed, 2 Sep 2015 12:37:51 +0300
From:	Stas Sergeev <stsp@...t.ru>
To:	Andy Lutomirski <luto@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux kernel <linux-kernel@...r.kernel.org>,
	"Andrew Bird (Sphere Systems)" <ajb@...eresystems.co.uk>
Subject: stop breaking dosemu (Re: x86/kconfig/32: Rename CONFIG_VM86 and
 default it to 'n')

https://lkml.org/lkml/2015/7/21/208

Guys, you gonna be kidding.
Is this a new trend of breaking dosemu, or what?

> VM86 is entirely broken if ptrace, syscall auditing, or
> NOHZ_FULL is in use.  The code is a big undocumented mess, it's
> a real PITA to test, and it looks like a big chunk of vm86_32.c

It is a CPU feature that kernel should support, and always
did without any problems. If it started to have problems because
of your actions, then you can as well fix your code.

 > No one should be using it anyway. Use DOSBOX or KVM instead.

Have you done the benchmarks between dosbox and dosemu
before saying that? Please do, thanks. (don't forget to include
dosemu2 in your benchmarks too, as it outperforms both)

> Let's accelerate its slow death.


 > + Enabling this option adds considerable attack surface to the
 > + kernel and slows down system calls and exception handling.

Yes, I realize that threatening people with the "considerable attack 
surface"
is a good way to "accelerate its slow death", but please care to explain
that attack surface, thankyou.
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