lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <E1Ii1oL-0005I3-00@gondolin.me.apana.org.au>
Date:	Wed, 17 Oct 2007 13:51:17 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	npiggin@...e.de (Nick Piggin)
Cc:	mikulas@...ax.karlin.mff.cuni.cz, arjan@...radead.org,
	linux-kernel@...r.kernel.org,
	virtualization <virtualization@...ts.linux-foundation.org>
Subject: Re: LFENCE instruction (was: [rfc][patch 3/3] x86: optimise barriers)

Nick Piggin <npiggin@...e.de> wrote:
>
> Also, for non-wb memory. I don't think the Intel document referenced
> says anything about this, but the AMD document says that loads can pass
> loads (page 8, rule b).
> 
> This is why our rmb() is still an lfence.

BTW, Xen (in particular, the code in drivers/xen) uses mb/rmb/wmb
instead of smp_mb/smp_rmb/smp_wmb when it accesses memory that's
shared with other Xen domains or the hypervisor.

The reason this is necessary is because even if a Xen domain is
UP the hypervisor might be SMP.

It would be nice if we can have these adopt the new SMP barriers
on x86 instead of the IO ones as they currently do.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists