Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1533066

Re: [patch net / RFC] net: fec: increase frame size limitation to actually available buffer

Show all headers | View raw

On 2016/11/30 15:36, Nikita Yushchenko wrote:
>> But I think it is not necessary since the driver don't support jumbo frame.
> 
> Hardcoded 1522 raises two separate issues.
> 
> (1) When DSA is in use, frames processed by FEC chip contain DSA tag and
> thus can be larger than hardcoded limit of 1522. This issue is not
> FEC-specific, any driver that hardcodes maximum frame size to 1522 (many
> do) will have this issue if used with DSA.
> 
> Clean solution for this must take into account that difference between
> MTU and max frame size is no longer known at compile time. Actually this
> is the case even without DSA, due to VLANs: max frame size is (MTU + 18)
> without VLANs, but (MTU + 22) with VLANs. However currently drivers tend
> to ignore this and hardcode 22.  With DSA, 22 is not enough, need to add
> switch-specific tag size to that.
> 
> Not yet sure how to handle this. DSA-specific API to find out tag size
> could be added, but generic solution should handle all cases of dynamic
> difference between MTU and max frame size, not only DSA.

BTW I'm trying to introduce envelope frames to solve this kind of problems.
http://marc.info/?t=147496691500005&r=1&w=2
http://marc.info/?t=147496691500003&r=1&w=2
http://marc.info/?t=147496691500002&r=1&w=2
http://marc.info/?t=147496691500004&r=1&w=2
http://marc.info/?t=147496691500001&r=1&w=2

It needs jumbo frame support of NICs though.

Regards,
Toshiaki Makita

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[patch net / RFC] net: fec: increase frame size limitation to actually available buffer Nikita Yushchenko <nikita.yoush@cogentembedded.com> - 2016-11-29 19:40 +0100
  Re: [patch net / RFC] net: fec: increase frame size limitation to  actually available buffer Nikita Yushchenko <nikita.yoush@cogentembedded.com> - 2016-11-30 07:40 +0100
    RE: [patch net / RFC] net: fec: increase frame size limitation to  actually available buffer Andy Duan <fugang.duan@nxp.com> - 2016-11-30 08:40 +0100
    Re: [patch net / RFC] net: fec: increase frame size limitation to  actually available buffer Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> - 2016-11-30 09:40 +0100
      DSA vs envelope frames Nikita Yushchenko <nikita.yoush@cogentembedded.com> - 2016-11-30 16:00 +0100
        Re: DSA vs envelope frames Andrew Lunn <andrew@lunn.ch> - 2016-11-30 16:20 +0100
          Re: DSA vs envelope frames Florian Fainelli <f.fainelli@gmail.com> - 2016-12-01 04:50 +0100
        Re: DSA vs envelope frames Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> - 2016-12-01 13:50 +0100
  RE: [patch net / RFC] net: fec: increase frame size limitation to  actually available buffer Andy Duan <fugang.duan@nxp.com> - 2016-11-30 11:20 +0100
  Re: [patch net / RFC] net: fec: increase frame size limitation to  actually available buffer Zefir Kurtisi <zefir.kurtisi@neratec.com> - 2016-11-30 17:20 +0100

csiph-web