Re: DMA error when sg->offset value is greater than PAGE_SIZE in Intel IOMMU

[Harsh Jain <Harsh@chelsio.com>]

On 28-09-2017 18:35, Raj, Ashok wrote:
> Thanks for trying that Harsh. 
>
> sp_off turns of super page support. Which this mode, do you still see offsets greater than 4k?
Yes, offset greater than 4k is still there. Refer below.
[56732.774872] offset 4110 len 76 dma addr 3a531200e dma len 76
[56732.804187] offset 4110 len 84 dma addr 3a63b200e dma len 84
[56732.805104] offset 4110 len 68 dma addr 3a531200e dma len 68
[56732.806870] offset 4110 len 56 dma addr 3a531200e dma len 56
[56732.808987] offset 4110 len 56 dma addr 3a531200e dma len 56
[56732.811215] offset 4110 len 56 dma addr 3a531200e dma len 56
[56732.813155] offset 4110 len 56 dma addr 3a531200e dma len 56
[56732.814823] offset 4110 len 56 dma addr 3a531200e dma len 56
[56732.816481] offset 4110 len 56 dma addr 3a531200e dma len 56
[56732.818159] offset 4110 len 56 dma addr 3a531200e dma len 56
[56732.819712] offset 4110 len 56 dma addr 3a531200e dma len 56
[56732.821629] offset 4110 len 56 dma addr 3a531200e dma len 56
[root@heptagon linux_t4_build]#
[root@heptagon linux_t4_build]#
[root@heptagon linux_t4_build]# cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-4.9.51 root=UUID=ccbb7f18-b3f0-43df-89de-07521e9c02fe ro intel_iommu=sp_off crashkernel=auto rhgb quiet rhgb quiet console=ttyS0,115200, console=tty0 LANG=en_US.UTF-8

>
> On Thu, Sep 28, 2017 at 07:08:21PM +0530, Harsh Jain wrote:
>>
>> Today I tried with "Intel_iommu=sp_off" boot option. Traffic runs without any error for more than 1 hrs. What magic this option did? :)
> Cheers,
> Ashok