From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Sagi Grimberg <sagi@grimberg.me>,
Marta Rybczynska <mrybczyn@kalray.eu>,
Charles Machalow <csm10495@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-nvme <linux-nvme@lists.infradead.org>, axboe <axboe@fb.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] nvme: change nvme_passthru_cmd64's result field.
Date: Mon, 4 Nov 2019 16:29:16 +0100 [thread overview]
Message-ID: <20191104152916.GB17050@lst.de> (raw)
In-Reply-To: <20191104150151.GA26808@redsun51.ssa.fujisawa.hgst.com>
On Tue, Nov 05, 2019 at 12:01:51AM +0900, Keith Busch wrote:
> On Mon, Nov 04, 2019 at 03:56:57PM +0100, Marta Rybczynska wrote:
> > ----- On 4 Nov, 2019, at 15:51, Charles Machalow csm10495@gmail.com wrote:
> >
> > > For this one yes, UAPI size changes. Though I believe this IOCTL
> > > hasn't been in a released Kernel yet (just RC). Technically it may be
> > > changeable as a fix until the next Kernel is released. I do think its
> > > a useful enough
> > > change to warrant a late fix.
> >
> > The old one is in UAPI for years. The new one is not yet, right. I'm OK
> > to change the new structure. To have compatibility you would have to use
> > the new structure (at least its size) in the user space code. This is
> > what you'd liek to do?
>
> Charles is proposing only to modify the recently introduced 64-bit ioctl
> struct without touching the existing 32 bit version. He just wanted the
> lower 32-bits of the 64-bit result to occupy the same space as the 32-bit
> ioctl's result. That space in the 64-bit version is currently occupied
> by an implicit struct padding.
Except on 32-bit x86, which does not have the padding. Which is why
the current layout is so bad, as it breaks 32-it x86 compat.
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next prev parent reply other threads:[~2019-11-04 15:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-31 5:03 [PATCH] nvme: change nvme_passthru_cmd64's result field Charles Machalow
2019-10-31 13:39 ` Christoph Hellwig
[not found] ` <CANSCoS8rN6g7u6iG4SRTcXjdj68cbimvX1n1Ex+FBAkhAAivJA@mail.gmail.com>
2019-10-31 13:59 ` Christoph Hellwig
2019-10-31 15:39 ` Charles Machalow
2019-10-31 13:59 ` Charles Machalow
2019-11-04 14:34 ` Marta Rybczynska
2019-11-04 14:51 ` Charles Machalow
2019-11-04 14:56 ` Marta Rybczynska
2019-11-04 15:01 ` Keith Busch
2019-11-04 15:29 ` Christoph Hellwig [this message]
2019-11-04 15:32 ` Keith Busch
2019-11-04 15:01 ` Charles Machalow
2019-11-04 15:16 ` Marta Rybczynska
2019-11-04 15:20 ` Charles Machalow
2019-11-04 15:30 ` Christoph Hellwig
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