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Subject: Re: [tip:x86/asm] x86/umip: Add emulation code for UMIP instructions
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Anvin <hpa@zytor.com>,
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From: Denys Vlasenko <dvlasenk@redhat.com>
Message-ID: <68c11f7a-cd26-0fdc-0ac5-939a72c22227@redhat.com>
Date: Wed, 8 Nov 2017 18:09:29 +0100
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On 11/08/2017 05:57 PM, Linus Torvalds wrote:
> On Wed, Nov 8, 2017 at 8:53 AM, Denys Vlasenko <dvlasenk@redhat.com> wrote:
>> We can postpone enabling UMIP by default by a year or so.
>> By this time, new Wine will be on majority of users' machines.
> 
> So you are suggesting we run unnecessarily insecure, only in order to
> not do the emulation that we already have the code for and that the
> patch implements?

We ran insecure in this way for ~25 years.

> Why?

To avoid having to maintain more obscure, rarely executed code.