linux-kernel - Re: kexec fails if OF_UNITTEST=y (was: Re: [PATCH v2] Removes OF_UNITTEST dependency on OF

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Message-ID: <CAMuHMdU+DCVNyjd0s4TLz93=3AFGoq_QWvRbg3nCej7a3mX2BA@mail.gmail.com>
Date:	Tue, 17 Mar 2015 07:52:44 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Rob Herring <robherring2@...il.com>
Cc:	Gaurav Minocha <gaurav.minocha.os@...il.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...aro.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: kexec fails if OF_UNITTEST=y (was: Re: [PATCH v2] Removes
 OF_UNITTEST dependency on OF_DYNAMIC config symbol)

Hi Rob,

On Tue, Mar 17, 2015 at 1:25 AM, Rob Herring <robherring2@...il.com> wrote:
> On Mon, Mar 16, 2015 at 5:58 AM, Geert Uytterhoeven
> <geert@...ux-m68k.org> wrote:
>> On Fri, Jan 23, 2015 at 2:03 PM, Geert Uytterhoeven
>> <geert@...ux-m68k.org> wrote:
>>> On Sun, Jan 11, 2015 at 8:19 AM, Gaurav Minocha
>>> <gaurav.minocha.os@...il.com> wrote:
>>>> This patch intends to remove the unittests dependency on
>>>> the functions defined in dynamic.c. So, rather than calling
>>>> of_attach_node defined in dynamic.c, minimal functionality
>>>> required to attach a new node is re-defined in unittest.c.
>>>> Also, now after executing the tests the test data is not
>>>> removed from the device tree so there is no need to call
>>>> of_detach_node.
>>>
>>> Could there be unwanted side effects of not removing the test data?
>>
>> Unfortunately I found a regression introduced by commit 3ce04b4a9fdc30b6
>> ("Removes OF_UNITTEST dependency on OF_DYNAMIC config symbol").
>>
>> If the test data is still present, kexec (kexec-tools 2.0.7 released 24
>> November 2014, 1:2.0.7-5 in Debian) fails with:
>>
>> unrecoverable error: short read
>> from"/proc/device-tree//testcase-data/large-property-PAGE_SIZEx8"
>>
>> Granted, this is a bug in kexec-tools, but I'm reporting it anyway, as it is
>> a kernel regression with existing userspace.
>>
>> I believe this bug was fixed in kexec-tools by commit d1932cd592e2a6aa
>> ("kexec/fs2dt: Use slurp_file_len to avoid partial read of files"), but I
>> haven't tested the fix yet.
>
> Is OF_UNITTEST enabled by default in Debian or this is a custom
> kernel? Perhaps we should require a command line option to actually
> populate the test data and run the tests?

It's not that bad, this is a custom kernel. I just had it still
enabled by accident.

I guess making it modular is not that easy?

> We just need more tests to slow down the boot enough people will not
> enable them by default. ;)

Apart from slowing down the boot, most tests don't have side effects.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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