[PATCH] doc: add PMD known issue

[PATCH] doc: add PMD known issue

[Mingjin Ye]

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.
-- 
2.25.1

Re: [PATCH] doc: add PMD known issue

[Stephen Hemminger]

On Thu, 20 Apr 2023 06:14:29 +0000
Mingjin Ye <mingjinx.ye@intel.com> wrote:

> Add a known issue: ASLR feature causes core dump.
> 
> Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
> ---

Please provide back trace.
This should be fixable.
Fixing a bug is always better than documenting it.

Re: [PATCH] doc: add PMD known issue

[Bruce Richardson]

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

[PATCH v2] doc: add PMD known issue

[Mingjin Ye]

Add a known issue: The ixgbe_vf driver is not multi-process safe.

Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
---
v2: Modify issue description reason.
---
 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..9fb3c39bf4 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)
+
+VF driver is not multi-process safe
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+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 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.
-- 
2.25.1

RE: [PATCH v2] doc: add PMD known issue

[Zhang, Qi Z]

> -----Original Message-----
> From: Mingjin Ye <mingjinx.ye@intel.com>
> Sent: Saturday, May 6, 2023 6:03 PM
> To: dev@dpdk.org
> Cc: Yang, Qiming <qiming.yang@intel.com>; stable@dpdk.org; Zhou, YidingX
> <yidingx.zhou@intel.com>; Ye, MingjinX <mingjinx.ye@intel.com>; Wu,
> Wenjun1 <wenjun1.wu@intel.com>
> Subject: [PATCH v2] doc: add PMD known issue
> 
> Add a known issue: The ixgbe_vf driver is not multi-process safe.
> 
> Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
> ---
> v2: Modify issue description reason.
> ---
>  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..9fb3c39bf4 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)
> +
> +VF driver is not multi-process safe
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +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 memory space is randomized.
> +The secondary process calls the function address shared by the primary
> +process, resulting in a core dump.

Which function did we encounter the issue with? Is this a bug in the PMD? In a multi-process scenario, we should not assume that the addresses of functions are identical across different processes. Additionally, this issue should not be related ASLR because the primary and secondary processes could be two different applications but still share the same DPDK library.

> +
> +   .. 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.
> --
> 2.25.1

[PATCH v3] doc: comment VF does not support multi-process

[Mingjin Ye]

Announcing that multi-process is not supported

Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
---
v2: Modify issue description reason.
---
V3: Modify description.
---
 doc/guides/nics/ixgbe.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
index b1d77ab7ab..816d614c33 100644
--- a/doc/guides/nics/ixgbe.rst
+++ b/doc/guides/nics/ixgbe.rst
@@ -461,3 +461,9 @@ 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)
+
+VF driver does not support multi-process
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The VF driver does not support multi-process. And some function pointers
+in the case of multi-process are not set correctly.
-- 
2.25.1

Re: [PATCH v3] doc: comment VF does not support multi-process

[Stephen Hemminger]

On Tue, 16 May 2023 10:22:05 +0000
Mingjin Ye <mingjinx.ye@intel.com> wrote:

> Announcing that multi-process is not supported
> 
> Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
> ---
> v2: Modify issue description reason.
> ---
> V3: Modify description.
> ---
>  doc/guides/nics/ixgbe.rst | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
> index b1d77ab7ab..816d614c33 100644
> --- a/doc/guides/nics/ixgbe.rst
> +++ b/doc/guides/nics/ixgbe.rst
> @@ -461,3 +461,9 @@ 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)  
> +
> +VF driver does not support multi-process
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +The VF driver does not support multi-process. And some function pointers
> +in the case of multi-process are not set correctly.

This is best done by updating doc/guides/nic/features/ixgbe_vf.ini

That is enough. Don't need to add note in ixgbe.rst.

RE: [PATCH v3] doc: comment VF does not support multi-process

[Ye, MingjinX]

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: 2023年5月16日 23:18
> To: Ye, MingjinX <mingjinx.ye@intel.com>
> Cc: dev@dpdk.org; Yang, Qiming <qiming.yang@intel.com>;
> stable@dpdk.org; Zhou, YidingX <yidingx.zhou@intel.com>; Wu, Wenjun1
> <wenjun1.wu@intel.com>
> Subject: Re: [PATCH v3] doc: comment VF does not support multi-process
> 
> On Tue, 16 May 2023 10:22:05 +0000
> Mingjin Ye <mingjinx.ye@intel.com> wrote:
> 
> > Announcing that multi-process is not supported
> >
> > Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
> > ---
> > v2: Modify issue description reason.
> > ---
> > V3: Modify description.
> > ---
> >  doc/guides/nics/ixgbe.rst | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/doc/guides/nics/ixgbe.rst b/doc/guides/nics/ixgbe.rst
> > index b1d77ab7ab..816d614c33 100644
> > --- a/doc/guides/nics/ixgbe.rst
> > +++ b/doc/guides/nics/ixgbe.rst
> > @@ -461,3 +461,9 @@ 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)
> > +
> > +VF driver does not support multi-process
> > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > +
> > +The VF driver does not support multi-process. And some function
> > +pointers in the case of multi-process are not set correctly.
> 
> This is best done by updating doc/guides/nic/features/ixgbe_vf.ini
> 
> That is enough. Don't need to add note in ixgbe.rst.

I will send the v4 version as soon as possible with a better solution.

[PATCH v4] doc: update ixgbe VF features list

[Mingjin Ye]

The ixgbe VF driver is not multi-process aware. Some function pointers are
not set correctly in multi-process situations.

Remove the multiprocess aware feature from the features list.

Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>
---
v2: Modify issue description reason.
---
V3: Modify description.
---
V4: Removed the multiprocess aware feature.
---
 doc/guides/nics/features/ixgbe_vf.ini | 1 -
 1 file changed, 1 deletion(-)

diff --git a/doc/guides/nics/features/ixgbe_vf.ini b/doc/guides/nics/features/ixgbe_vf.ini
index e14325045c..299ccd4b61 100644
--- a/doc/guides/nics/features/ixgbe_vf.ini
+++ b/doc/guides/nics/features/ixgbe_vf.ini
@@ -32,7 +32,6 @@ Tx descriptor status = Y
 Basic stats          = Y
 Extended stats       = Y
 Registers dump       = Y
-Multiprocess aware   = Y
 FreeBSD              = Y
 Linux                = Y
 Windows              = Y
-- 
2.25.1

RE: [PATCH v4] doc: update ixgbe VF features list

[Zhang, Qi Z]

> -----Original Message-----
> From: Mingjin Ye <mingjinx.ye@intel.com>
> Sent: Wednesday, May 17, 2023 6:04 PM
> To: dev@dpdk.org
> Cc: Yang, Qiming <qiming.yang@intel.com>; stable@dpdk.org; Zhou, YidingX
> <yidingx.zhou@intel.com>; Ye, MingjinX <mingjinx.ye@intel.com>; Wu,
> Wenjun1 <wenjun1.wu@intel.com>
> Subject: [PATCH v4] doc: update ixgbe VF features list
> 
> The ixgbe VF driver is not multi-process aware. Some function pointers are
> not set correctly in multi-process situations.
> 
> Remove the multiprocess aware feature from the features list.
> 
> Signed-off-by: Mingjin Ye <mingjinx.ye@intel.com>

Acked-by: Qi Zhang <qi.z.zhang@intel.com>

Applied to dpdk-next-net-intel.

Thanks
Qi