Re: [dpdk-dev] [PATCH] eal: disable IOVA mode detection by default

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

> -----Original Message-----
> From: Yigit, Ferruh
> Sent: Wednesday, November 1, 2017 9:07 AM
> To: Thomas Monjalon; Richardson, Bruce; Gonzalez Monroy, Sergio
> Cc: dev@dpdk.org; Yigit, Ferruh; Tan, Jianfeng; Santosh Shukla
> Subject: [PATCH] eal: disable IOVA mode detection by default
> 
> Fix kernel crash with KNI because KNI requires physical addresses.
> 
> A config option introduced to disable IOVA mode detection and to set it
> to physical address by default. Disabling config option will enable IOVA
> mode detection.
> 
> When there is no intension to use KNI, it is safe to enable detection.
> 
> Config option disable IOVA mode detection by default to be sure only who
> is aware of result enable it.
> 
> Fixes: 72d013644bd6 ("mem: honor IOVA mode in malloc virt2phy")
> 
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> ---
> Cc: Jianfeng Tan <jianfeng.tan@intel.com>
> Cc: Santosh Shukla <santosh.shukla@caviumnetworks.com>
> Cc: Thomas Monjalon <thomas@monjalon.net>

Refer to how vhost-kernel works, we may leverage a memory region table to do the translation. The bad side is it's less efficient than current phys_to_virt.

Another side, we did not check the result of phys_to_virt, that's why kernel crashes.

Thanks,
Jianfeng