Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Maarten ter Huurne <maarten@treewalker.org>
To:     mips-creator-ci20-dev@googlegroups.com
Cc:     "H. Nikolaus Schaller" <hns@goldelico.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Ralf Baechle <ralf@linux-mips.org>,
        Paul Burton <paul.burton@mips.com>, linux-mips@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@openphoenux.org>
Subject: Re: MIPS: bug: gettimeofday syscall broken on CI20 board
Date:   Thu, 28 Nov 2019 14:29:45 +0100
Message-ID: <4807842.gtHLO0kk0V@hyperion>
In-Reply-To: <D1CE4D1E-9A42-4FAE-90A9-615C38B979C0@goldelico.com>
References: <18788C50-F29B-4BD7-89F6-B056FF490214@goldelico.com> <7b6275c7-ab2b-a647-6bf7-d5e1c4523c98@arm.com> <D1CE4D1E-9A42-4FAE-90A9-615C38B979C0@goldelico.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thursday, 28 November 2019 13:33:17 CET H. Nikolaus Schaller wrote:
> Hi Vincenzo,
> 
> > Am 28.11.2019 um 13:21 schrieb Vincenzo Frascino
> > <vincenzo.frascino@arm.com>:> 
> > [...]
> > The the lib that provides the gettimeofday() changes accordingly
> > with vdso_data. 5.4 and 4.19 have 2 different vdso libraries as
> > well.
> 
> Yes, that is what I have assumed what happens. How do these libs go
> into an existing and working root-file-system with Debian Stretch?

I'm a novice when it comes to vDSO, so someone please correct me if I'm 
wrong.

From what I read vDSO is a library in the sense that it exports ELF 
symbols that applications and other libraries (libc in particular) can 
use, but it is not a file on disk.

As such, which rootfs you use shouldn't matter, since the vDSO is not in 
the rootfs. Instead, it is contained in the kernel image. Searching for 
"linux-vdso.so.1" on packages.debian.org indeed returns no hits.

There is a check in arch/mips/vdso/Makefile that disables vDSO on MIPS 
when building the kernel with binutils < 2.25. I don't know if that is 
in any way related to this issue.

Bye,
		Maarten