linux-kernel - Re: [RFC] /dev/ioasid uAPI proposal

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Message-ID: <20210601173138.GM1002214@nvidia.com>
Date:   Tue, 1 Jun 2021 14:31:38 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     "Tian, Kevin" <kevin.tian@...el.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Liu Yi L <yi.l.liu@...ux.intel.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "Alex Williamson (alex.williamson@...hat.com)\"\"" 
        <alex.williamson@...hat.com>, David Woodhouse <dwmw2@...radead.org>
Subject: Re: [RFC] /dev/ioasid uAPI proposal

On Tue, Jun 01, 2021 at 04:47:15PM +0800, Jason Wang wrote:
 
> We can open up to ~0U file descriptors, I don't see why we need to restrict
> it in uAPI.

There are significant problems with such large file descriptor
tables. High FD numbers man things like select don't work at all
anymore and IIRC there are more complications.

A huge number of FDs for typical usages should be avoided.

Jason