netconsole not working on bridge+atlantic

netconsole not working on bridge+atlantic

[Chris Adams]

I have a system with an Aquantia AQC107 NIC connected to a bridge (for
VM NICs).  I set up netconsole on it, and it logs that it configures
correctly in dmesg, but it doesn't actually send anything (or log any
errors).  Any ideas?

This is on Fedora 37, updated to distro kernel 6.3.3-100.fc37.x86_64.
It hasn't worked for some time (not sure exactly when).
-- 
Chris Adams <linux@cmadams.net>

Re: netconsole not working on bridge+atlantic

[Florian Fainelli]

+CC maintainers,

On 5/19/2023 5:38 PM, Chris Adams wrote:
> I have a system with an Aquantia AQC107 NIC connected to a bridge (for
> VM NICs).  I set up netconsole on it, and it logs that it configures
> correctly in dmesg, but it doesn't actually send anything (or log any
> errors).  Any ideas?

It does not look like there is a ndo_poll_controller callback 
implemented by the atlantic driver which is usually a prerequisite to 
supporting netconsole.

> 
> This is on Fedora 37, updated to distro kernel 6.3.3-100.fc37.x86_64.
> It hasn't worked for some time (not sure exactly when).

Does that mean that it worked up to a certain point and then stopped?
-- 
Florian

Re: netconsole not working on bridge+atlantic

[Chris Adams]

Once upon a time, Florian Fainelli <f.fainelli@gmail.com> said:
> On 5/19/2023 5:38 PM, Chris Adams wrote:
> >I have a system with an Aquantia AQC107 NIC connected to a bridge (for
> >VM NICs).  I set up netconsole on it, and it logs that it configures
> >correctly in dmesg, but it doesn't actually send anything (or log any
> >errors).  Any ideas?
> 
> It does not look like there is a ndo_poll_controller callback
> implemented by the atlantic driver which is usually a prerequisite
> to supporting netconsole.

Is that something that netconsole (or anything else in the kernel) could
check and warn about?  Is there a way other than looking at the source
(and knowing what to look for) to tell which NICs do or don't support
netconsole?  I searched around and didn't see that netconsole is only
expected to work with some NICs, or has certain requirements for
working.

> >This is on Fedora 37, updated to distro kernel 6.3.3-100.fc37.x86_64.
> >It hasn't worked for some time (not sure exactly when).
> 
> Does that mean that it worked up to a certain point and then stopped?

I'm not sure, I didn't check it for a while (I only use it when
something isn't working right, and that doesn't happen much).  It's
possible it hasn't worked since I added the Aquantia NIC.
-- 
Chris Adams <linux@cmadams.net>

Re: netconsole not working on bridge+atlantic

[Jakub Kicinski]

On Fri, 19 May 2023 22:09:24 -0500 Chris Adams wrote:
> Once upon a time, Florian Fainelli <f.fainelli@gmail.com> said:
> > On 5/19/2023 5:38 PM, Chris Adams wrote:  
> > >I have a system with an Aquantia AQC107 NIC connected to a bridge (for
> > >VM NICs).  I set up netconsole on it, and it logs that it configures
> > >correctly in dmesg, but it doesn't actually send anything (or log any
> > >errors).  Any ideas?  
> > 
> > It does not look like there is a ndo_poll_controller callback
> > implemented by the atlantic driver which is usually a prerequisite
> > to supporting netconsole.  

I don't think ndo_poll_controller is strictly necessary any more.
If absent core will poll all NAPI instances of the driver with budget
of 0.

> Is that something that netconsole (or anything else in the kernel) could
> check and warn about?  Is there a way other than looking at the source
> (and knowing what to look for) to tell which NICs do or don't support
> netconsole?  I searched around and didn't see that netconsole is only
> expected to work with some NICs, or has certain requirements for
> working.
> 
> > >This is on Fedora 37, updated to distro kernel 6.3.3-100.fc37.x86_64.
> > >It hasn't worked for some time (not sure exactly when).  
> > 
> > Does that mean that it worked up to a certain point and then stopped?  
> 
> I'm not sure, I didn't check it for a while (I only use it when
> something isn't working right, and that doesn't happen much).  It's
> possible it hasn't worked since I added the Aquantia NIC.

You can try to use the kfree_skb tracepoint to see where the netcons
skbs get dropped.