From: Bharat Kumar Gogada <bharatku@xilinx.com>
To: Matthew Wilcox <willy@infradead.org>,
Dan Williams <dan.j.williams@intel.com>
Cc: "linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"jack@suse.cz" <jack@suse.cz>
Subject: RE: DAX filesystem support on ARMv8
Date: Thu, 14 Nov 2019 06:54:43 +0000 [thread overview]
Message-ID: <MN2PR02MB6336070627E66ED8AE646BACA5710@MN2PR02MB6336.namprd02.prod.outlook.com> (raw)
In-Reply-To: <20191112220212.GC7934@bombadil.infradead.org>
>
> On Tue, Nov 12, 2019 at 09:15:18AM -0800, Dan Williams wrote:
> > On Mon, Nov 11, 2019 at 6:12 PM Bharat Kumar Gogada
> <bharatku@xilinx.com> wrote:
> > >
> > > Hi All,
> > >
> > > As per Documentation/filesystems/dax.txt
> > >
> > > The DAX code does not work correctly on architectures which have
> > > virtually mapped caches such as ARM, MIPS and SPARC.
> > >
> > > Can anyone please shed light on dax filesystem issue w.r.t ARM architecture
> ?
> >
> > The concern is VIVT caches since the kernel will want to flush pmem
> > addresses with different virtual addresses than what userspace is
> > using. As far as I know, ARMv8 has VIPT caches, so should not have an
> > issue. Willy initially wrote those restrictions, but I am assuming
> > that the concern was managing the caches in the presence of virtual
> > aliases.
>
> The kernel will also access data at different virtual addresses from userspace.
> So VIVT CPUs will be mmap/read/write incoherent, as well as being flush
> incoherent.
Thanks a lot Wilcox and Dan for clarification.
So the above restriction only applies to ARM architectures with VIVT caches and not
for VIPT caches.
Regards,
Bharat
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
next prev parent reply other threads:[~2019-11-14 6:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-12 2:12 DAX filesystem support on ARMv8 Bharat Kumar Gogada
2019-11-12 9:49 ` Jan Kara
2019-11-12 17:15 ` Dan Williams
2019-11-12 22:02 ` Matthew Wilcox
2019-11-14 6:54 ` Bharat Kumar Gogada [this message]
2019-12-01 18:54 ` Jon Masters
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=MN2PR02MB6336070627E66ED8AE646BACA5710@MN2PR02MB6336.namprd02.prod.outlook.com \
--to=bharatku@xilinx.com \
--cc=dan.j.williams@intel.com \
--cc=jack@suse.cz \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nvdimm@lists.01.org \
--cc=viro@zeniv.linux.org.uk \
--cc=willy@infradead.org \
/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).