Re: [PATCH] doc: add PMD known issue

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Apr 20, 2023 at 06:14:29AM +0000, Mingjin Ye wrote:
> Add a known issue: ASLR feature causes core dump.
> 
> Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
> ---
>  doc/guides/nics/ixgbe.rst | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
> index b1d77ab7ab..c346e377e2 100644
> --- a/doc/guides/nics/ixgbe.rst
> +++ b/doc/guides/nics/ixgbe.rst
> @@ -461,3 +461,18 @@ show bypass config
>  Show the bypass configuration for a bypass enabled NIC using the lowest port on the NIC::
>  
>     testpmd> show bypass config (port_id)
> +
> +ASLR feature causes core dump
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +Core dump may occur when we start secondary processes on the vf port.
> +Mainstream Linux distributions have the ASLR feature enabled by default,
> +and the text segment of the process's memory space is randomized.
> +The secondary process calls the function address shared by the primary
> +process, resulting in a core dump.
> +
> +   .. Note::
> +
> +	  Support for ASLR features varies by distribution. Redhat and
> +	  Centos series distributions work fine. Ubuntu distributions
> +	  will core dump, other Linux distributions are unknown.
> -- 

I disagree about this description of the bug. ASLR is not the problem;
instead driver is just not multi-process aware and uses the same pointers
in both primary and secondary processes. You will hit this issue even
without ASLR if primary and secondary processes use different static
binaries. Therefore, IMHO, title should be that the VF driver is not
multi-process safe, rather than pinning the blame on ASLR.

/Bruce