linux-kernel - Re: allow larger than require DMA masks

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:   Tue, 24 Sep 2019 23:25:54 +0200
From:   Christoph Hellwig <hch@....de>
To:     James Bottomley <James.Bottomley@...senPartnership.com>
Cc:     Sven Schnelle <svens@...ckframe.org>,
        Christoph Hellwig <hch@....de>, Helge Deller <deller@....de>,
        linux-parisc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: allow larger than require DMA masks

On Mon, Sep 23, 2019 at 08:59:42PM -0400, James Bottomley wrote:
> > 	if (mask > ~0U)
> > »     »       return 0;
> > 
> > Removing the if() makes the DMA mapping work. It's almost midnight
> > here, so i won't look into that any further today. Does anyone have
> > an opinion on this behaviour? Otherwise i will look a bit more into
> > this in the next days.
> 
> The reason for the if was to kick the device into 32 bit descriptors,
> which are usually more efficient, especially with older dual descriptor
> format cards like we have on parisc systems.

These days we use the dma_get_required_mask API to query for that.

Svens patch looks right for how we are now using the DMA mask setting
API.