netdev - Re: [PATCH 3/20][BNX2]: Add 40-bit DMA workaround for 5708.

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, 02 May 2007 16:28:22 -0700
From:	"Michael Chan" <mchan@...adcom.com>
To:	"David Miller" <davem@...emloft.net>
cc:	jeff@...zik.org, "netdev" <netdev@...r.kernel.org>
Subject: Re: [PATCH 3/20][BNX2]: Add 40-bit DMA workaround for 5708.

On Wed, 2007-05-02 at 14:45 -0700, David Miller wrote:
> From: "Michael Chan" <mchan@...adcom.com>
> Date: Wed, 02 May 2007 14:27:49 -0700
> 
> > I see.  So IA64 always uses the SWIOTLB when it doesn't have IOMMU then?
> > 
> > I'm a bit confused.  Is it enough to just set the DMA mask to 40-bit and
> > forget about all this checking?  I thought that wasn't enough.  A tx
> > packet can be anywhere in 64-bit memory.  When it gets to the driver,
> > pci_map will not do any translation even if DMA mask is set to 40-bit if
> > it doesn't have IOMMU.  Is that right?
> 
> If the buffer doesn't meet the DMA mask specification, it should do
> bounce buffering.
> 
> Have a look at lib/swiotlb.c, that is exactly what it appears to
> be doing.
> 

OK.  Is it correct to assume that all 64-bit systems using 64-bit
dma_addr_t will either have real IOMMUs or will use SWIOTLB?  If this is
true, we can just set the DMA mask to what is supported by the hardware
and let pci_map_xxx() handle all necessary translations or bounce
buffering.

-
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