netdev - Re: [PATCH 2/3] x86_64: Define 128-bit memory-mapped I/O operations

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: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 22 Aug 2012 10:30:54 -0400
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	David Miller <davem@...emloft.net>, tglx@...utronix.de,
	mingo@...hat.com, netdev@...r.kernel.org,
	linux-net-drivers@...arflare.com, x86@...nel.org
Subject: Re: [PATCH 2/3] x86_64: Define 128-bit memory-mapped I/O operations

On Wed, Aug 22, 2012 at 03:24:59PM +0100, Ben Hutchings wrote:
> -#ifdef EFX_USE_QWORD_IO
> +#if defined(EFX_USE_OWORD_IO)
> +       _efx_writeo(efx, value->u128, reg);
> +#elif defined(EFX_USE_QWORD_IO)
>         _efx_writeq(efx, value->u64[0], reg + 0);
>         _efx_writeq(efx, value->u64[1], reg + 8);
>  #else

This looks like a perfect fit for write combining.  I have traces showing 
that enabling write combining on MMIO does indeed generate a single PCIe 
transaction on at least a couple of different current systems.  Why is 
that not an option?

		-ben
-- 
"Thought is the essence of where you are now."
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html