From: tndave <tushar.n.d...@oracle.com> 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.
