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linux/serial.h warning w/ 4.2.4p6

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udo...@gmail.com

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Jan 31, 2009, 5:10:54 AM1/31/09
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Hello,

While building ntp 4.2.4p6 for use with LinuxPPS I noticed:

configure: WARNING: linux/serial.h: present but cannot be compiled
configure: WARNING: linux/serial.h: check for missing prerequisite
headers?
configure: WARNING: linux/serial.h: see the Autoconf documentation
configure: WARNING: linux/serial.h: section "Present But Cannot Be
Compiled"
configure: WARNING: linux/serial.h: proceeding with the preprocessor's
result
configure: WARNING: linux/serial.h: in the future, the compiler will
take precedence
configure: WARNING: ## ------------------------------ ##
configure: WARNING: ## Report this to the ntp lists. ##
configure: WARNING: ## ------------------------------ ##

This was not the first time, but now I have to ask:

I this a problem on my Fedora 10 system, an issue with the ntp code or
something else?
Is anybody looking into this issue?

Please post!
Udo

Harlan Stenn

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Feb 1, 2009, 5:07:41 PM2/1/09
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>>> In article <6c52c70d-ccd9-45c0...@n33g2000pri.googlegroups.com>, udo...@gmail.com writes:

udovdh> Hello, While building ntp 4.2.4p6 for use with LinuxPPS I noticed:

udovdh> configure: WARNING: linux/serial.h: present but cannot be compiled
udovdh> configure: WARNING: linux/serial.h: check for missing prerequisite headers?
udovdh> I this a problem on my Fedora 10 system, an issue with the ntp code
udovdh> or something else? Is anybody looking into this issue?

Apparently, compiling linux/serial.h on your platform requires some extra
headers.

If you look thru config.log you will see the section of code that runs to
figure out if linux/serial.h is present and compilable.

If you can figure out what other headers are needed to run that test without
complaint I can add them to the test for this header in configure.ac

--
Harlan Stenn <st...@ntp.org>
http://ntpforum.isc.org - be a member!

udo...@gmail.com

unread,
Feb 2, 2009, 11:04:09 AM2/2/09
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On Feb 1, 11:07 pm, Harlan Stenn <st...@ntp.org> wrote:
> If you can figure out what other headers are needed to run that test without
> complaint I can add them to the test for this header in configure.ac

I found:

configure:49412: checking linux/serial.h usability
configure:49424: gcc -c -m32 -march=i686 -mtune=c3-2 -pipe -mmmx -msse
-fomit-frame-pointer -ffast-math -finline-functions -mfpmath=sse,387 -
Os -pie -fPIE -Wall -Wcast-qual -Wmissing-prototypes -Wpointer-arith -
Wshadow -Wstrict-prototypes conftest.c >&5
In file included from conftest.c:246:
/usr/include/linux/serial.h:184: error: expected specifier-qualifier-
list before '__u32'

This is about the first __u32 in:

struct serial_rs485 {
__u32 flags; /* RS485 feature flags */
#define SER_RS485_ENABLED (1 << 0)
#define SER_RS485_RTS_ON_SEND (1 << 1)
#define SER_RS485_RTS_AFTER_SEND (1 << 2)
__u32 delay_rts_before_send; /* Milliseconds */
__u32 padding[6]; /* Memory is cheap, new
structs
are a royal PITA .. */
};


Which is the serial.h at /lib/modules/2.6.28.2/build/include/linux/
serial.h which is needed to build ntpd with LinuxPPS support:
http://wiki.enneenne.com/index.php/LinuxPPS_installation#The_userland_tools

(i.e.: see the links)

Currently I don't know how what the solution is.

Uwe Klein

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Feb 2, 2009, 12:00:06 PM2/2/09
to
udo...@gmail.com wrote:
> On Feb 1, 11:07 pm, Harlan Stenn <st...@ntp.org> wrote:
>
>>If you can figure out what other headers are needed to run that test without
>>complaint I can add them to the test for this header in configure.ac
>
>
> I found:
>
> configure:49412: checking linux/serial.h usability
> configure:49424: gcc -c -m32 -march=i686 -mtune=c3-2 -pipe -mmmx -msse
> -fomit-frame-pointer -ffast-math -finline-functions -mfpmath=sse,387 -
> Os -pie -fPIE -Wall -Wcast-qual -Wmissing-prototypes -Wpointer-arith -
> Wshadow -Wstrict-prototypes conftest.c >&5
> In file included from conftest.c:246:
> /usr/include/linux/serial.h:184: error: expected specifier-qualifier-
> list before '__u32'

Which version of the linux kernel are you using?

I can compile the following code on all my boxes.
#################################

# include <linux/serial.h>


struct serial_rs485 *serial;

#################################

uwe

udo...@gmail.com

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Feb 2, 2009, 1:25:07 PM2/2/09
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On Feb 2, 6:00 pm, Uwe Klein <uwe_klein_habertw...@t-online.de> wrote:
> udo...@gmail.com wrote:
> > On Feb 1, 11:07 pm, Harlan Stenn <st...@ntp.org> wrote:
>
> >>If you can figure out what other headers are needed to run that test without
> >>complaint I can add them to the test for this header in configure.ac
>
> > I found:
(...)

> > /usr/include/linux/serial.h:184: error: expected specifier-qualifier-
> > list before '__u32'
>
> Which version of the linux kernel are you using?

I use Fedora 10 with kernel-headers-2.6.27.12-170.2.5.fc10.i386 and my
own kernel at 2.6.28.2 with ntp-pps-2.6.28-rc6-bis.diff.

Uwe Klein

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Feb 3, 2009, 6:07:20 AM2/3/09
to

That seems to (have been?) be a bug in recent versions.
http://markmail.org/message/xpche3qt3b6lsmey
http://www.google.com/search?q=linux%2Fserial.h+__u32


uwe

udo...@gmail.com

unread,
Feb 3, 2009, 9:54:07 AM2/3/09
to
On Feb 3, 12:07 pm, Uwe Klein <uwe_klein_habertw...@t-online.de>
wrote:
> udo...@gmail.com wrote:
(........)

> > I use Fedora 10 with kernel-headers-2.6.27.12-170.2.5.fc10.i386 and my
> > own kernel at 2.6.28.2 with ntp-pps-2.6.28-rc6-bis.diff.
>
> That seems to (have been?) be a bug in recent versions.
>        http://markmail.org/message/xpche3qt3b6lsmey
>        http://www.google.com/search?q=linux%2Fserial.h+__u32

Thanks.
This means no change for ntpd and wait for the fix to land in the
mainline kernels?


Udo

Uwe Klein

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Feb 3, 2009, 10:12:46 AM2/3/09
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The posting from Alan Cox seems to promise that:
http://linux.derkeiler.com/Mailing-Lists/Kernel/2008-12/msg09446.html

uwe

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