linux-kernel - Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

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Date:	Wed, 07 May 2014 19:50:18 +0200
From:	Alexandre Julliard <julliard@...ehq.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Sven Joachim <svenjoac@....de>,
	Brian Gerst <brgerst@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	stable <stable@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

"H. Peter Anvin" <hpa@...or.com> writes:

> On 05/07/2014 09:57 AM, Linus Torvalds wrote:
>> 
>> Afaik, 16-bit programs under wine already need
>> 
>>   echo 0 > /proc/sys/vm/mmap_min_addr
>> 
>> because they want to map things at address 0, so this isn't a new concept.
>> 
>
> I think that applies to DOSEMU, but not to Wine.

Yes, there are a few exceptions, but most Win16 apps run fine without
mapping address 0.

> I'm somewhat curious if this program you have is actually a 32-bit
> program or if it is really a 16-bit program wrapped in a 32-bit
> installer of some kind.  Hard to know without seeing the program in
> question.

It could be a mix of both, there are various thunking mechanisms that
allow 32-bit binaries to use 16-bit components. This was pretty common
in the Win95 days.

-- 
Alexandre Julliard
julliard@...ehq.org
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