Re: i40e: Kernel unaligned access due to 'struct i40e_dma_mem' being 'packed'
On 01/30/2016 04:17 AM, tndave wrote: On 01/27/2016 10:56 PM, David Miller wrote: From: tndave Date: Wed, 27 Jan 2016 17:50:14 -0800 Hi, i40e driver has 'struct i40e_dma_mem' defined with 'packed' directive causing kernel unaligned errors on sparc (when 40e_allocate_dma_mem_d() is being called) log_unaligned: 1031 callbacks suppressed Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 This can be fixed with get_unaligned/put_unaligned(). However I don't see 'struct i40e_dma_mem' is being directly shoved into NIC hardware. But instead fields of the struct are being read and used for hardware (e.g. dma_addr_t pa). For the test, I remove __packed, and i40e driver and HW works fine. (of course kernel unaligned errors are gone too). My question is, does 'struct i40e_dma_mem' required to be __packed? People get overzealoud with __packed. And even if it doesn't cause unaligned accesses like this, it generates terrible code (byte at a time accesses to words) on several architectures. True. For the same reason I want to clarify if __packed is actually needed? instead of fixing it with get_unaligned/put_unaligned()! We are having this issue on multiple sparc servers. It would be really helpful to have feedback from i40e driver folks. Thanks. -Tushar
Re: i40e: Kernel unaligned access due to 'struct i40e_dma_mem' being 'packed'
On 01/27/2016 10:56 PM, David Miller wrote: From: tndave Date: Wed, 27 Jan 2016 17:50:14 -0800 Hi, i40e driver has 'struct i40e_dma_mem' defined with 'packed' directive causing kernel unaligned errors on sparc (when 40e_allocate_dma_mem_d() is being called) log_unaligned: 1031 callbacks suppressed Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 This can be fixed with get_unaligned/put_unaligned(). However I don't see 'struct i40e_dma_mem' is being directly shoved into NIC hardware. But instead fields of the struct are being read and used for hardware (e.g. dma_addr_t pa). For the test, I remove __packed, and i40e driver and HW works fine. (of course kernel unaligned errors are gone too). My question is, does 'struct i40e_dma_mem' required to be __packed? People get overzealoud with __packed. And even if it doesn't cause unaligned accesses like this, it generates terrible code (byte at a time accesses to words) on several architectures. True. For the same reason I want to clarify if __packed is actually needed? instead of fixing it with get_unaligned/put_unaligned()! -Tushar
Re: i40e: Kernel unaligned access due to 'struct i40e_dma_mem' being 'packed'
From: tndave Date: Wed, 27 Jan 2016 17:50:14 -0800 > Hi, > > i40e driver has 'struct i40e_dma_mem' defined with 'packed' directive > causing kernel unaligned errors on sparc (when > 40e_allocate_dma_mem_d() > is being called) > > log_unaligned: 1031 callbacks suppressed > Kernel unaligned access at TPC[448ae8] > dma_4v_alloc_coherent+0x188/0x2e0 > Kernel unaligned access at TPC[448ae8] > dma_4v_alloc_coherent+0x188/0x2e0 > Kernel unaligned access at TPC[448ae8] > dma_4v_alloc_coherent+0x188/0x2e0 > Kernel unaligned access at TPC[448ae8] > dma_4v_alloc_coherent+0x188/0x2e0 > > This can be fixed with get_unaligned/put_unaligned(). However I don't > see 'struct i40e_dma_mem' is being directly shoved into NIC hardware. > But instead fields of the struct are being read and used for hardware > (e.g. dma_addr_t pa). For the test, I remove __packed, and i40e driver > and HW works fine. (of course kernel unaligned errors are gone too). > My question is, does 'struct i40e_dma_mem' required to be __packed? People get overzealoud with __packed. And even if it doesn't cause unaligned accesses like this, it generates terrible code (byte at a time accesses to words) on several architectures.
i40e: Kernel unaligned access due to 'struct i40e_dma_mem' being 'packed'
Hi, i40e driver has 'struct i40e_dma_mem' defined with 'packed' directive causing kernel unaligned errors on sparc (when 40e_allocate_dma_mem_d() is being called) log_unaligned: 1031 callbacks suppressed Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 Kernel unaligned access at TPC[448ae8] dma_4v_alloc_coherent+0x188/0x2e0 This can be fixed with get_unaligned/put_unaligned(). However I don't see 'struct i40e_dma_mem' is being directly shoved into NIC hardware. But instead fields of the struct are being read and used for hardware (e.g. dma_addr_t pa). For the test, I remove __packed, and i40e driver and HW works fine. (of course kernel unaligned errors are gone too). My question is, does 'struct i40e_dma_mem' required to be __packed? Thanks. -Tushar
