linux-kernel - Re: [PATCH 4/7] x86/vm86: Move vm86 fields out of thread

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Message-ID: <20150721063509.GB5110@gmail.com>
Date:	Tue, 21 Jul 2015 08:35:09 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Brian Gerst <brgerst@...il.com>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 4/7] x86/vm86: Move vm86 fields out of thread_struct


* Andy Lutomirski <luto@...capital.net> wrote:

> On Mon, Jul 20, 2015 at 11:28 PM, Ingo Molnar <mingo@...nel.org> wrote:
> >
> > * Brian Gerst <brgerst@...il.com> wrote:
> >
> >> Allocate a separate structure for the vm86 fields.
> >
> > Why is this allocated dynamically? This structure is not very large, and a 
> > hole in thread_struct isn't that big of an issue - compared to additional 
> > fragility introduced by the (mostly untested by normal apps) dynamic 
> > allocation here ...
> >
> > I don't mind the introduction of the sub-structure in itself, but please 
> > embedd it in thread_struct.
> 
> This ends up being several hundred bytes, I think, due to including an entire 
> struct pt_regs.  Do we really want to enlarge thread_struct that much for 
> something that's essentially never used?

Ok, I only judged by the first patch, I did not realize it becomes that much 
larger in later patches.

I've extended the changelog to explain this properly.

Thanks,

	Ingo
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