linux-kernel - Re: [PATCH V2 2/3] powerpc: Add support for swiotlb on 32-bit

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]

Message-ID: <4A173B72.5000201@goop.org>
Date:	Fri, 22 May 2009 16:55:30 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Ian Campbell <Ian.Campbell@...citrix.com>
CC:	Becky Bruce <beckyb@...nel.crashing.org>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	"linuxppc-dev@...abs.org" <linuxppc-dev@...abs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 2/3] powerpc: Add support for swiotlb on 32-bit

Ian Campbell wrote:
> On Thu, 2009-05-21 at 14:27 -0400, Becky Bruce wrote:
>   
>> I can work with that, but it's going to be a bit inefficient, as I  
>> actually need the dma_addr_t, not the phys_addr_t, so I'll have to  
>> convert.  In every case, this is a conversion I've already done and  
>> that I need in the calling code as well. 
>>     
>
> Does
>
>     dma_addr_t dma_map_range(struct device *hwdev, phys_addr_t addr,
>     size_t size);
>
> work for you?
>
> If the range does not need mapping then it returns the dma address, if
> you needed to calculate the dma address anyway to figure out if mapping
> is required then this is fine. If the range does need mapping then it
> returns NULL.
>   

My only concern is whether dma_addr_t == 0 is actually equivalent to 
NULL.  That is, can we be sure that address 0 will never be used?

Taking dma_alloc_coherent as a model, we could have something like:

    int dma_map_range(struct device *hwdev, phys_addr_t addr, size_t size, dma_addr_t *dma_addrp);
      

where *dma_addrp is set if the function returns success (bool return 
type might be clearer).

    J
--
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/