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Groups > linux.kernel > #1673937

Re: New NTB API Issue

From Logan Gunthorpe <logang@deltatee.com>
Newsgroups linux.kernel
Subject Re: New NTB API Issue
Date 2017-06-24 01:10 +0200
Message-ID <tVFSa-8si-15@gated-at.bofh.it> (permalink)
References (9 earlier) <tVwFb-2Eg-1@gated-at.bofh.it> <tVA66-4Fr-9@gated-at.bofh.it> <tVC7U-66A-7@gated-at.bofh.it> <tVDx0-6Sb-25@gated-at.bofh.it> <tVEW5-7RD-9@gated-at.bofh.it>
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On 23/06/17 04:06 PM, Allen Hubbe wrote:
> From: Logan Gunthorpe
>> But any translation can be
>> programmed by any peer.
> 
> That doesn't seem safe.  Even though it can be done as you say, would it not be better to have each specific translation under the control of exactly one driver?
> 
> If drivers can reach across and set the translation of any peer bar, they would still need to negotiate among N peers which one sets which other's translation.

Yup. In a dual host setup its not a problem seeing only the one peer
will ever set any of the memory windows. In the multi-host setup, there
has to be implicit or explicit negotiation as to which memory window
connects to which peer.

The hardware also implements locking so if two peers try to mess with
the same translation, the worst that can happen is the last peer's
settings will take effect or one peer will see an error.

Logan

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Thread

New NTB API Issue Logan Gunthorpe <logang@deltatee.com> - 2017-06-22 18:20 +0200
  Re: New NTB API Issue Logan Gunthorpe <logang@deltatee.com> - 2017-06-22 20:50 +0200
    RE: New NTB API Issue "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-06-23 00:20 +0200
      Re: New NTB API Issue Logan Gunthorpe <logang@deltatee.com> - 2017-06-23 00:20 +0200
        RE: New NTB API Issue "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-06-23 00:50 +0200
          Re: New NTB API Issue Logan Gunthorpe <logang@deltatee.com> - 2017-06-23 00:50 +0200
            RE: New NTB API Issue "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-06-23 15:20 +0200
              Re: New NTB API Issue Logan Gunthorpe <logang@deltatee.com> - 2017-06-23 19:00 +0200
                RE: New NTB API Issue "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-06-23 21:10 +0200
                Re: New NTB API Issue Logan Gunthorpe <logang@deltatee.com> - 2017-06-23 22:40 +0200
                RE: New NTB API Issue "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-06-24 00:10 +0200
                Re: New NTB API Issue Logan Gunthorpe <logang@deltatee.com> - 2017-06-24 01:10 +0200
                Re: New NTB API Issue Serge Semin <fancer.lancer@gmail.com> - 2017-06-23 23:50 +0200
                Re: New NTB API Issue Logan Gunthorpe <logang@deltatee.com> - 2017-06-24 00:10 +0200
                RE: New NTB API Issue "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-06-24 00:10 +0200
  RE: New NTB API Issue "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-06-22 20:50 +0200

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