linux-kernel - Re: [patch] paravirt: VDSO page is essential

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Message-ID: <45EC0EB7.7080300@qumranet.com>
Date:	Mon, 05 Mar 2007 14:36:07 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Roland McGrath <roland@...hat.com>,
	Andi Kleen <ak@...e.de>, Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [patch] paravirt: VDSO page is essential

Ingo Molnar wrote:
> Subject: [patch] paravirt: VDSO page is essential
> From: Ingo Molnar <mingo@...e.hu>
>
> commit 3bbf54725467d604698721384d858b5983b87e8f disables the VDSO for 
> CONFIG_PARAVIRT kernels. This #ifdeffery was a bad change: the VDSO is 
> an essential component of Linux, and this change forces all of them to 
> use int $0x80 - including sane ones like KVM. (If a hypervisor does not 
> handle the VDSO properly then it can work things around via the vdso=0 
> boot option. Or CONFIG_PARAVIRT should not have been merged. But in any 
> case, it is a basic taste issue: we DO NOT #ifdef around core features 
> like this!)
>
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> ---
>  arch/i386/kernel/sysenter.c |    4 ----
>  1 file changed, 4 deletions(-)
>
> Index: linux/arch/i386/kernel/sysenter.c
> ===================================================================
> --- linux.orig/arch/i386/kernel/sysenter.c
> +++ linux/arch/i386/kernel/sysenter.c
> @@ -27,11 +27,7 @@
>   * Should the kernel map a VDSO page into processes and pass its
>   * address down to glibc upon exec()?
>   */
> -#ifdef CONFIG_PARAVIRT
> -unsigned int __read_mostly vdso_enabled = 0;
> -#else
>  unsigned int __read_mostly vdso_enabled = 1;
> -#endif
>  
>  EXPORT_SYMBOL_GPL(vdso_enabled);
>  
>   

Can't paravirt patch the syscall instruction like it does the rest of 
the kernel?

[is someone keeping track of the number of patchsites? e.g. at what date 
will the entire kernel be generated at boot time?]


-- 
error compiling committee.c: too many arguments to function

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