From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"olivier.matz@6wind.com" <olivier.matz@6wind.com>,
"stable@dpdk.org" <stable@dpdk.org>
Subject: Re: [dpdk-stable] [PATCH] net/virtio-user: fix not working on 32-bit system
Date: Fri, 14 Apr 2017 06:56:01 +0000 [thread overview]
Message-ID: <ED26CBA2FAD1BF48A8719AEF02201E365119F79A@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <20170414062017.GM7333@yliu-dev.sh.intel.com>
> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu@linux.intel.com]
> Sent: Friday, April 14, 2017 2:20 PM
> To: Tan, Jianfeng
> Cc: dev@dpdk.org; olivier.matz@6wind.com; stable@dpdk.org
> Subject: Re: [PATCH] net/virtio-user: fix not working on 32-bit system
>
> On Fri, Apr 14, 2017 at 05:53:55AM +0000, Tan, Jianfeng wrote:
> > > > diff --git a/drivers/net/virtio/virtqueue.h
> b/drivers/net/virtio/virtqueue.h
> > > > index f9e3736..f43ea70 100644
> > > > --- a/drivers/net/virtio/virtqueue.h
> > > > +++ b/drivers/net/virtio/virtqueue.h
> > > > @@ -72,7 +72,8 @@ struct rte_mbuf;
> > > > * Return the physical address (or virtual address in case of
> > > > * virtio-user) of mbuf data buffer.
> > > > */
> > > > -#define VIRTIO_MBUF_ADDR(mb, vq) (*(uint64_t *)((uintptr_t)(mb)
> +
> > > (vq)->offset))
> > > > +#define VIRTIO_MBUF_ADDR(mb, vq) \
> > > > + ((uint64_t)((uintptr_t)(*(void **)((uintptr_t)(mb) + (vq)->offset))))
> > >
> > > The "void **" cast makes it a bit complex (thus hard to read). I think
> > > following should work?
> >
> > Yes, uintptr_t can work. I thought void ** is easier to understand, meaning
> a convert to a pointer which pointing to a pointer.
>
> It's twisted, isn't it? :)
>
> > I usually use uintptr_t only for converter from pointer to integer, not the
> opposite way.
>
> Yes, that's a typical usage. But the fact of the matter is uintptr_t
> represents the word size, which is exactly what needed in this case.
Another fold, if you refer to the definition of struct rte_mbuf, the first field is defined as void * instead of uintptr_t. I think that why I prefer to use ((void *)*) in the beginning.
Thanks,
Jianfeng
>
> --yliu
> >
> > >
> > > (uint64_t(*(uintptr_t *)((uintptr_t)(mb) + (vq)->offset)))
> > >
> > > Besides, it deserves a comment.
> >
> > Will add comment in next version.
> >
> > Thanks,
> > Jianfeng
> >
> > >
> > > --yliu
> > >
> > > > #else
> > > > #define VIRTIO_MBUF_ADDR(mb, vq) ((mb)->buf_physaddr)
> > > > #endif
> > > > --
> > > > 2.7.4
next prev parent reply other threads:[~2017-04-14 6:56 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 14:12 Jianfeng Tan
2017-04-14 5:32 ` Yuanhan Liu
2017-04-14 5:53 ` Tan, Jianfeng
2017-04-14 6:20 ` Yuanhan Liu
2017-04-14 6:56 ` Tan, Jianfeng [this message]
2017-04-14 7:01 ` Yuanhan Liu
2017-04-14 7:14 ` Tan, Jianfeng
2017-04-19 2:30 ` [dpdk-stable] [PATCH v2] " Jianfeng Tan
2017-04-19 5:53 ` Yuanhan Liu
2017-04-19 6:21 ` Tan, Jianfeng
2017-04-19 6:24 ` Yuanhan Liu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ED26CBA2FAD1BF48A8719AEF02201E365119F79A@SHSMSX103.ccr.corp.intel.com \
--to=jianfeng.tan@intel.com \
--cc=dev@dpdk.org \
--cc=olivier.matz@6wind.com \
--cc=stable@dpdk.org \
--cc=yuanhan.liu@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).