lkml.org 
[lkml]   [2018]   [Jun]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] net: nixge: Add __packed attribute to DMA descriptor struct
From
Date
On 06/19/2018 09:54 AM, Moritz Fischer wrote:
> Add __packed attribute to DMA descriptor structure in order to
> make sure that the DMA engine's alignemnt requirements are met.
>
> Fixes commit 492caffa8a1a ("net: ethernet: nixge: Add support for
> National Instruments XGE netdev")
> Signed-off-by: Moritz Fischer <mdf@kernel.org>
> ---
>
> Hi David,
>
> this addresses an issue where padding occured breaking the alignment
> in the array the descriptors are allocated in coherent memory.
> This was discovered when we tried to bring up the driver via a PCIe
> bridge on x86.

How could padding be inserted given than all of the structure members
are naturally aligned (all u32 type). Compiler bug?

Also

>
> Thanks,
>
> Moritz
>
> ---
> drivers/net/ethernet/ni/nixge.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/ni/nixge.c b/drivers/net/ethernet/ni/nixge.c
> index 09f674ec0f9e..fea0e994324b 100644
> --- a/drivers/net/ethernet/ni/nixge.c
> +++ b/drivers/net/ethernet/ni/nixge.c
> @@ -122,7 +122,7 @@ struct nixge_hw_dma_bd {
> u32 sw_id_offset;
> u32 reserved5;
> u32 reserved6;
> -};
> +} __packed;
>
> struct nixge_tx_skb {
> struct sk_buff *skb;
>


--
Florian

\
 
 \ /
  Last update: 2018-06-19 19:15    [W:0.083 / U:0.272 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site