From: Arnd Bergmann <arnd@arndb.de>
To: Avi Kivity <avi@qumranet.com>
Cc: kvm-devel@lists.sourceforge.net, akpm@osdl.org,
linux-kernel@vger.kernel.org
Subject: Re: [kvm-devel] [PATCH] KVM: Avoid using vmx instruction directly
Date: Thu, 9 Nov 2006 15:42:30 +0100 [thread overview]
Message-ID: <200611091542.31101.arnd@arndb.de> (raw)
In-Reply-To: <45532EE3.4000104@qumranet.com>
On Thursday 09 November 2006 14:36, Avi Kivity wrote:
>
> >
> > I'm not an expert on inline assembly, but don't you need an extra
> > '"m" (phys_addr)' to make sure that gcc actually puts the variable
> > on the stack instead of passing a NULL pointer as '"a"(&phys_addr)'?
>
> Taking a variable's address should force its contents into memory (like
> calling an uninlined function with &var).
No it doesn't. You're not telling gcc that the inline assembly cares
about the contents of the variable, so it could be a reference to
a stack slot while the contents are still in a register. Or gcc
might move the assignment of phys_addr to after the inline assembly.
Arnd <><
next prev parent reply other threads:[~2006-11-09 14:42 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-09 11:08 [PATCH] KVM: Avoid using vmx instruction directly Avi Kivity
2006-11-09 13:29 ` [kvm-devel] " Arnd Bergmann
2006-11-09 13:36 ` Avi Kivity
2006-11-09 14:42 ` Arnd Bergmann [this message]
2006-11-09 14:52 ` Avi Kivity
2006-11-09 16:37 ` Arnd Bergmann
2006-11-09 16:51 ` Avi Kivity
2006-11-09 23:39 ` Jeremy Fitzhardinge
2006-11-10 12:46 ` Martin Schwidefsky
2006-11-10 19:38 ` Jeremy Fitzhardinge
2006-11-21 18:35 ` H. Peter Anvin
2006-11-21 19:41 ` Avi Kivity
2006-11-21 20:50 ` Jeremy Fitzhardinge
2006-11-22 6:42 ` Avi Kivity
2006-11-22 9:10 ` Jeremy Fitzhardinge
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