Debian Bug report logs - #660288
Please enable CONFIG_KALLSYMS_ALL

Package: src:linux; Maintainer for src:linux is Debian Kernel Team <debian-kernel@lists.debian.org>;

Reported by: tabbott@mit.edu

Date: Fri, 17 Feb 2012 21:57:02 UTC

Severity: wishlist

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Report forwarded to debian-bugs-dist@lists.debian.org, Debian Kernel Team <debian-kernel@lists.debian.org>:
Bug#660288; Package linux-2.6. (Fri, 17 Feb 2012 21:57:05 GMT) Full text and rfc822 format available.

Acknowledgement sent to Tim Abbott <tim.abbott@oracle.com>:
New Bug report received and forwarded. Copy sent to Debian Kernel Team <debian-kernel@lists.debian.org>. (Fri, 17 Feb 2012 21:57:05 GMT) Full text and rfc822 format available.

Message #5 received at submit@bugs.debian.org (full text, mbox):

From: Tim Abbott <tim.abbott@oracle.com>
To: submit@bugs.debian.org
Subject: Please enable CONFIG_KALLSYMS_ALL
Date: Fri, 17 Feb 2012 15:35:06 -0500
Package: linux-2.6
Severity: wishlist

(Moving this topic from a debian-kernel thread to the BTS).

Would it be possible to turn on CONFIG_KALLSYMS_ALL in the Debian kernel 
for Wheezy? It's a useful debugging option, and makes it easier to 
implement useful tools like Ksplice that inspect the code and data 
structures of the running kernel, in particular in relation to operating 
on modules (one can use System.map to look up addresses for data 
structures in the core kernel). Most other major Linux distributions 
have had CONFIG_KALLSYMS_ALL enabled in their kernels for some time now 
(RHEL, Fedora, Ubuntu, etc.).

The discussion so far of why this option is useful on the debian-kernel 
thread is at:
<http://lists.debian.org/debian-kernel/2012/01/msg01017.html>.

        -Tim Abbott




Information forwarded to debian-bugs-dist@lists.debian.org, Debian Kernel Team <debian-kernel@lists.debian.org>:
Bug#660288; Package linux-2.6. (Sun, 03 Jun 2012 02:54:06 GMT) Full text and rfc822 format available.

Acknowledgement sent to Ben Hutchings <ben@decadent.org.uk>:
Extra info received and forwarded to list. Copy sent to Debian Kernel Team <debian-kernel@lists.debian.org>. (Sun, 03 Jun 2012 02:54:06 GMT) Full text and rfc822 format available.

Message #10 received at 660288@bugs.debian.org (full text, mbox):

From: Ben Hutchings <ben@decadent.org.uk>
To: Tim Abbott <tim.abbott@oracle.com>
Cc: 660288@bugs.debian.org
Subject: Re: Please enable CONFIG_KALLSYMS_ALL
Date: Sun, 03 Jun 2012 03:51:59 +0100
[Message part 1 (text/plain, inline)]
On Fri, 2012-02-17 at 15:35 -0500, Tim Abbott wrote:
> Package: linux-2.6
> Severity: wishlist
> 
> (Moving this topic from a debian-kernel thread to the BTS).
> 
> Would it be possible to turn on CONFIG_KALLSYMS_ALL in the Debian kernel 
> for Wheezy? It's a useful debugging option, and makes it easier to 
> implement useful tools like Ksplice that inspect the code and data 
> structures of the running kernel, in particular in relation to operating 
> on modules (one can use System.map to look up addresses for data 
> structures in the core kernel). Most other major Linux distributions 
> have had CONFIG_KALLSYMS_ALL enabled in their kernels for some time now 
> (RHEL, Fedora, Ubuntu, etc.).
> 
> The discussion so far of why this option is useful on the debian-kernel 
> thread is at:
> <http://lists.debian.org/debian-kernel/2012/01/msg01017.html>.

So I think you're saying that you need this to make ksplice work.
I would be much more interested in helping you to do that if you would
start releasing source to ksplice patches.

Ben.

-- 
Ben Hutchings
Knowledge is power.  France is bacon.
[signature.asc (application/pgp-signature, inline)]

Information forwarded to debian-bugs-dist@lists.debian.org, Debian Kernel Team <debian-kernel@lists.debian.org>:
Bug#660288; Package linux-2.6. (Mon, 04 Jun 2012 21:51:06 GMT) Full text and rfc822 format available.

Acknowledgement sent to Tim Abbott <tim.abbott@oracle.com>:
Extra info received and forwarded to list. Copy sent to Debian Kernel Team <debian-kernel@lists.debian.org>. (Mon, 04 Jun 2012 21:51:06 GMT) Full text and rfc822 format available.

Message #15 received at 660288@bugs.debian.org (full text, mbox):

From: Tim Abbott <tim.abbott@oracle.com>
To: Ben Hutchings <ben@decadent.org.uk>
Cc: 660288@bugs.debian.org
Subject: Re: Please enable CONFIG_KALLSYMS_ALL
Date: Mon, 04 Jun 2012 17:26:28 -0400
Hi Ben,

Your comment about source code is rather off-topic for this bug report, 
but since there seems to be a misunderstanding on this point, I'd like 
to clarify: Every Ksplice update tarball ships with a README file 
containing instructions on how to request the source code for that 
update from the appropriate people in Oracle Legal.  Anyone who follows 
those instructions can get a copy of the relevant source code.

To briefly clarify my original email, it is true that enabling 
CONFIG_KALLSYMS_ALL would make life slightly easier for Ksplice and 
similar tools that look at kernel data structures (e.g. debugging 
tools).  That said, Ksplice doesn't require CONFIG_KALLSYMS_ALL -- the 
Ksplice Uptrack service has been providing updates for systems running 
Debian Linux since 2009.  While your enabling CONFIG_KALLSYMS_ALL might 
allow us to delete like 50 lines of code 2 years from now when Squeeze 
reaches end of life, I submitted this bug report primarily because I'd 
like it to be the case that other folks developing similar innovative 
new technologies don't have to do the extra work of supporting 
!CONFIG_KALLSYMS_ALL in order to support all the major Linux 
distributions.  I hope you'll consider my suggestion on its technical 
merits.

        Best regards,
        -Tim Abbott

On 06/02/2012 10:51 PM, Ben Hutchings wrote:
> On Fri, 2012-02-17 at 15:35 -0500, Tim Abbott wrote:
>> Package: linux-2.6
>> Severity: wishlist
>>
>> (Moving this topic from a debian-kernel thread to the BTS).
>>
>> Would it be possible to turn on CONFIG_KALLSYMS_ALL in the Debian kernel
>> for Wheezy? It's a useful debugging option, and makes it easier to
>> implement useful tools like Ksplice that inspect the code and data
>> structures of the running kernel, in particular in relation to operating
>> on modules (one can use System.map to look up addresses for data
>> structures in the core kernel). Most other major Linux distributions
>> have had CONFIG_KALLSYMS_ALL enabled in their kernels for some time now
>> (RHEL, Fedora, Ubuntu, etc.).
>>
>> The discussion so far of why this option is useful on the debian-kernel
>> thread is at:
>> <http://lists.debian.org/debian-kernel/2012/01/msg01017.html>.
> So I think you're saying that you need this to make ksplice work.
> I would be much more interested in helping you to do that if you would
> start releasing source to ksplice patches.
>
> Ben.
>


-- 
        -Tim Abbott





Information forwarded to debian-bugs-dist@lists.debian.org, Debian Kernel Team <debian-kernel@lists.debian.org>:
Bug#660288; Package linux-2.6. (Thu, 07 Jun 2012 21:39:03 GMT) Full text and rfc822 format available.

Acknowledgement sent to Ben Hutchings <ben@decadent.org.uk>:
Extra info received and forwarded to list. Copy sent to Debian Kernel Team <debian-kernel@lists.debian.org>. (Thu, 07 Jun 2012 21:39:06 GMT) Full text and rfc822 format available.

Message #20 received at 660288@bugs.debian.org (full text, mbox):

From: Ben Hutchings <ben@decadent.org.uk>
To: Tim Abbott <tim.abbott@oracle.com>
Cc: 660288@bugs.debian.org
Subject: Re: Please enable CONFIG_KALLSYMS_ALL
Date: Thu, 7 Jun 2012 22:34:44 +0100
On Mon, Jun 04, 2012 at 05:26:28PM -0400, Tim Abbott wrote:
> Hi Ben,
> 
> Your comment about source code is rather off-topic for this bug
> report, but since there seems to be a misunderstanding on this
> point, I'd like to clarify: Every Ksplice update tarball ships with
> a README file containing instructions on how to request the source
> code for that update from the appropriate people in Oracle Legal.
> Anyone who follows those instructions can get a copy of the relevant
> source code.

I understand that Matthew Garrett tried to take up this offer a while
ago, and is still waiting for complete source code.  It doesn't seem
to be a good faith attempt to fulfil GPL obligations.

> To briefly clarify my original email, it is true that enabling
> CONFIG_KALLSYMS_ALL would make life slightly easier for Ksplice and
> similar tools that look at kernel data structures (e.g. debugging
> tools).

No doubt true, but it is also strictly redundant with debuginfo.

> That said, Ksplice doesn't require CONFIG_KALLSYMS_ALL --
> the Ksplice Uptrack service has been providing updates for systems
> running Debian Linux since 2009.  While your enabling
> CONFIG_KALLSYMS_ALL might allow us to delete like 50 lines of code 2
> years from now when Squeeze reaches end of life, I submitted this
> bug report primarily because I'd like it to be the case that other
> folks developing similar innovative new technologies don't have to
> do the extra work of supporting !CONFIG_KALLSYMS_ALL in order to
> support all the major Linux distributions.  I hope you'll consider
> my suggestion on its technical merits.
 
I'm going to have see a request from an actual other person before I
care to spend time on this.

(In case anyone else in the kernel team wants to proceed with this,
that's not a NAK.  The issue is that memory and/or flash partition
constraints make this unsuitable for some configurations, and you'll
need to work out which ones to enable it for.)

Ben

-- 
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
                                                              - Albert Camus




Information forwarded to debian-bugs-dist@lists.debian.org, Debian Kernel Team <debian-kernel@lists.debian.org>:
Bug#660288; Package linux-2.6. (Thu, 02 Aug 2012 21:09:03 GMT) Full text and rfc822 format available.

Acknowledgement sent to Tim Abbott <tim.abbott@oracle.com>:
Extra info received and forwarded to list. Copy sent to Debian Kernel Team <debian-kernel@lists.debian.org>. (Thu, 02 Aug 2012 21:09:03 GMT) Full text and rfc822 format available.

Message #25 received at 660288@bugs.debian.org (full text, mbox):

From: Tim Abbott <tim.abbott@oracle.com>
To: Ben Hutchings <ben@decadent.org.uk>
Cc: 660288@bugs.debian.org
Subject: Re: Please enable CONFIG_KALLSYMS_ALL
Date: Thu, 02 Aug 2012 16:31:28 -0400
[Message part 1 (text/plain, inline)]
On 06/07/2012 07:34 PM, Ben Hutchings wrote:
>
> On Mon, Jun 04, 2012 at 05:26:28PM -0400, Tim Abbott wrote:
> > Hi Ben,
> >
> > Your comment about source code is rather off-topic for this bug
> > report, but since there seems to be a misunderstanding on this
> > point, I'd like to clarify: Every Ksplice update tarball ships with
> > a README file containing instructions on how to request the source
> > code for that update from the appropriate people in Oracle Legal.
> > Anyone who follows those instructions can get a copy of the relevant
> > source code.
>
> I understand that Matthew Garrett tried to take up this offer a while
> ago, and is still waiting for complete source code.  It doesn't seem
> to be a good faith attempt to fulfil GPL obligations.
This is not my department, but as I understand it, Matthew Garrett 
received complete source code in response to each of his various 
requests for Ksplice source code.

> > To briefly clarify my original email, it is true that enabling
> > CONFIG_KALLSYMS_ALL would make life slightly easier for Ksplice and
> > similar tools that look at kernel data structures (e.g. debugging
> > tools).
>
> No doubt true, but it is also strictly redundant with debuginfo.
This is where I disagree.  Debuginfo is both huge (since it contains 
lots of data beyond the basic symbol information in kallsyms) and is 
also not necessarily available on user systems, meaning that any sort of 
patching or debugging tool intending to get wide use can't rely on it.  
Further, any system which contains third-party modules (open source or 
not) will not have symbol data for those modules unless the vendors of 
those third-party modules provide a separate debuginfo package (many do 
not); with kallsyms, you're guaranteed to have accurate information that 
comes from the modules that are actually loaded on the system.

As I think I mentioned before, when folks upgrade the kernel version on 
disk on a Debian system and don't immediately reboot (which folks do 
_all the time_ whether they're using Ksplice or not), and then load 
kernel modules, they'll get kernel modules from the upgraded kernel (at 
least in the common case where the ABI doesn't change). As a 
consequence, if you're any sort of debugging/instrumentation tool that 
inspects the running kernel's code, you need to be able to handle the 
case where the kernel is running modules that don't actually go with 
either the running kernel (via "uname -a") or the currently version of 
the linux-image-* package installed on disk. Trying to do anything to 
get symbol information in that sort of situation using debuginfo is a 
disaster; what you want is kallsyms.

> > That said, Ksplice doesn't require CONFIG_KALLSYMS_ALL --
> > the Ksplice Uptrack service has been providing updates for systems
> > running Debian Linux since 2009.  While your enabling
> > CONFIG_KALLSYMS_ALL might allow us to delete like 50 lines of code 2
> > years from now when Squeeze reaches end of life, I submitted this
> > bug report primarily because I'd like it to be the case that other
> > folks developing similar innovative new technologies don't have to
> > do the extra work of supporting !CONFIG_KALLSYMS_ALL in order to
> > support all the major Linux distributions.  I hope you'll consider
> > my suggestion on its technical merits.
>   
> I'm going to have see a request from an actual other person before I
> care to spend time on this.
>
> (In case anyone else in the kernel team wants to proceed with this,
> that's not a NAK.  The issue is that memory and/or flash partition
> constraints make this unsuitable for some configurations, and you'll
> need to work out which ones to enable it for.)
CONFIG_KALLSYMS_ALL adds less than 1% to the size of the kernel over 
CONFIG_KALLSYMS (obviously this depends on what options one had enabled 
in the first place), so only on truly embedded settings will that matter 
at all.  Could you at least just enable it for the architectures where 
none of Debian's stock kernels are designed for embedded environments 
(e.g. x86, sparc, power)?

        -Tim Abbott
[Message part 2 (text/html, inline)]

Information forwarded to debian-bugs-dist@lists.debian.org, Debian Kernel Team <debian-kernel@lists.debian.org>:
Bug#660288; Package linux-2.6. (Sun, 09 Sep 2012 19:15:03 GMT) Full text and rfc822 format available.

Acknowledgement sent to Ben Hutchings <ben@decadent.org.uk>:
Extra info received and forwarded to list. Copy sent to Debian Kernel Team <debian-kernel@lists.debian.org>. (Sun, 09 Sep 2012 19:15:03 GMT) Full text and rfc822 format available.

Message #30 received at 660288@bugs.debian.org (full text, mbox):

From: Ben Hutchings <ben@decadent.org.uk>
To: Tim Abbott <tim.abbott@oracle.com>
Cc: 660288@bugs.debian.org
Subject: Re: Please enable CONFIG_KALLSYMS_ALL
Date: Sun, 09 Sep 2012 20:13:32 +0100
[Message part 1 (text/plain, inline)]
On Thu, 2012-08-02 at 16:31 -0400, Tim Abbott wrote:
> On 06/07/2012 07:34 PM, Ben Hutchings wrote:
> 
> > 
> > On Mon, Jun 04, 2012 at 05:26:28PM -0400, Tim Abbott wrote:
> > > Hi Ben,
> > > 
> > > Your comment about source code is rather off-topic for this bug
> > > report, but since there seems to be a misunderstanding on this
> > > point, I'd like to clarify: Every Ksplice update tarball ships with
> > > a README file containing instructions on how to request the source
> > > code for that update from the appropriate people in Oracle Legal.
> > > Anyone who follows those instructions can get a copy of the relevant
> > > source code.
> > 
> > I understand that Matthew Garrett tried to take up this offer a while
> > ago, and is still waiting for complete source code.  It doesn't seem
> > to be a good faith attempt to fulfil GPL obligations.
> This is not my department, but as I understand it, Matthew Garrett
> received complete source code in response to each of his various
> requests for Ksplice source code.

I'm satisfied that this is no longer an issue.

[...]
> > I'm going to have see a request from an actual other person before I
> > care to spend time on this.

So this is no longer the case - but that is no guarantee that I will
find the time to deal with this before release.

> > (In case anyone else in the kernel team wants to proceed with this,
> > that's not a NAK.  The issue is that memory and/or flash partition
> > constraints make this unsuitable for some configurations, and you'll
> > need to work out which ones to enable it for.)
> CONFIG_KALLSYMS_ALL adds less than 1% to the size of the kernel over
> CONFIG_KALLSYMS (obviously this depends on what options one had
> enabled in the first place), so only on truly embedded settings will
> that matter at all.  Could you at least just enable it for the
> architectures where none of Debian's stock kernels are designed for
> embedded environments (e.g. x86, sparc, power)?

Yes, this will probably work.

Ben.

-- 
Ben Hutchings
Time is nature's way of making sure that everything doesn't happen at once.
[signature.asc (application/pgp-signature, inline)]

Changed Bug submitter to 'tabbott@mit.edu' from 'Tim Abbott <tim.abbott@oracle.com>' Request was from Ben Hutchings <ben@decadent.org.uk> to control@bugs.debian.org. (Sun, 09 Sep 2012 21:06:03 GMT) Full text and rfc822 format available.

Bug reassigned from package 'linux-2.6' to 'src:linux'. Request was from Moritz Muehlenhoff <jmm@debian.org> to control@bugs.debian.org. (Mon, 08 Jul 2013 16:09:31 GMT) Full text and rfc822 format available.

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