how to find when a symbol introduced into the kernel

how to find when a symbol introduced into the kernel

[Zhaohui Wang]

Hi all

To write multiple kernel version compatible programs, I need to know when a specific symbol (a struct or a function)were introduced in to the kernel tree

Binary search against multiple kernel sources is a way,but is still slow.Is there any fast way to use modern git technology to make my life easier?

Many thanks.

Best Regards
Zhaohui Wang



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how to find when a symbol introduced into the kernel

[Zhaohui Wang]

Hi all

To write multiple kernel version compatible programs, I need to know when a specific symbol (a struct or a function)were introduced in to the kernel tree

Binary search against multiple kernel sources is a way,but is still slow.Is there any fast way to use modern git technology to make my life easier?

Many thanks.

Best Regards
Zhaohui Wang

Re: how to find when a symbol introduced into the kernel

[Ben Nizette]

On Sat, 2008-06-14 at 18:11 -0400, Zhaohui Wang wrote:
> 
> Hi all
> 
> To write multiple kernel version compatible programs, I need to know when a specific symbol (a struct or a function)were introduced in to the kernel tree
> 
> Binary search against multiple kernel sources is a way,but is still slow.Is there any fast way to use modern git technology to make my life easier?
> 

You can see the last time a line in a file was touched with git-blame;
that might help.

	--Ben.
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Re: how to find when a symbol introduced into the kernel

[Ben Nizette]

On Sat, 2008-06-14 at 18:11 -0400, Zhaohui Wang wrote:
> 
> Hi all
> 
> To write multiple kernel version compatible programs, I need to know when a specific symbol (a struct or a function)were introduced in to the kernel tree
> 
> Binary search against multiple kernel sources is a way,but is still slow.Is there any fast way to use modern git technology to make my life easier?
> 

You can see the last time a line in a file was touched with git-blame;
that might help.

	--Ben.

Re: how to find when a symbol introduced into the kernel

[Calvin Walton]

On Sat, 2008-06-14 at 18:11 -0400, Zhaohui Wang wrote:
> 
> Hi all
> 
> To write multiple kernel version compatible programs, I need to know when a specific symbol (a struct or a function)were introduced in to the kernel tree
> 
> Binary search against multiple kernel sources is a way,but is still slow.Is there any fast way to use modern git technology to make my life easier?
> 
> Many thanks.

You're probably looking for the command
  git log -S functionname
a.k.a. the git pickaxe.

That will show you all of the commits that added or removed a line
containing the name you're interested in, and you can then check just
those changes to see what compatibility may have changed.

To find out what kernel release one of those commits went into, you can
use
  git describe <sha1-hash>
and it will report the last tagged kernel version before that commit was
added.

Hope that helps!

-- 
Calvin Walton <calvin.walton@gmail.com>

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Re: how to find when a symbol introduced into the kernel

[Calvin Walton]

On Sat, 2008-06-14 at 18:11 -0400, Zhaohui Wang wrote:
> 
> Hi all
> 
> To write multiple kernel version compatible programs, I need to know when a specific symbol (a struct or a function)were introduced in to the kernel tree
> 
> Binary search against multiple kernel sources is a way,but is still slow.Is there any fast way to use modern git technology to make my life easier?
> 
> Many thanks.

You're probably looking for the command
  git log -S functionname
a.k.a. the git pickaxe.

That will show you all of the commits that added or removed a line
containing the name you're interested in, and you can then check just
those changes to see what compatibility may have changed.

To find out what kernel release one of those commits went into, you can
use
  git describe <sha1-hash>
and it will report the last tagged kernel version before that commit was
added.

Hope that helps!

-- 
Calvin Walton <calvin.walton@gmail.com>

RE: how to find when a symbol introduced into the kernel

[Zhaohui Wang]

Hi all

Has anyone ever successfully tried sysrq key?

When  I press alt+sysrq+g , it always brought  up the evbug log, nothing
with sysrq special functionality happens

Anyone can tell me what should I do?


Best Regards
Zhao Wang



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(unknown)

[Alexei Babich]

Hi all,
How I can disable printk() output bufferization ? I need that printk() prints symbol-by-symbol or line-by-line.

Thank you.
-- 
Regards,
Alexei Babich, chematic engineer, OOO NPP "Rezonans", Chelyabinsk, Russia
http://www.rez.ru
Jabber ID: impatt@jabber.ru
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Re:

[Peter Teoh]

On Mon, May 19, 2008 at 6:57 PM, Alexei Babich <a.babich@rez.ru> wrote:
> Hi all,
> How I can disable printk() output bufferization ? I need that printk() prints symbol-by-symbol or line-by-line.
>

Check this out - since it has similar embedded requirements like yours
(what is a chematic engineer?):

http://tree.celinuxforum.org/pipermail/celinux-dev/2006-July/001261.html

Read the comments part of kernel/printk.c - printk() is an amazing
function, because it can be called in ANY CONTEXT.....which also means
that it cannot sleep.   But since u know many I/O function involved
some form of waiting, therefore printk() necessarily HAVE TO WRITE TO
A BUFFER, and it only write to the screen/console whenever it is
allowed to sleep (which involved holding a  console semaphore).

In short, printk() sometimes will output to screen directly, esp when
u are not in the interrupt context.   Otherwise it may just buffer for
later delivery.

> Thank you.
> --
> Regards,
> Alexei Babich, chematic engineer, OOO NPP "Rezonans", Chelyabinsk, Russia
> http://www.rez.ru
> Jabber ID: impatt@jabber.ru
> --


-- 
Regards,
Peter Teoh
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Re:

[Alexei Babich]

> Check this out - since it has similar embedded requirements like yours
> (what is a chematic engineer?):
I ment circuit, not schematic, and that's a misprint in addition :)

> http://tree.celinuxforum.org/pipermail/celinux-dev/2006-July/001261.html
Thank you for link.

> 
> Read the comments part of kernel/printk.c - printk() is an amazing
> function, because it can be called in ANY CONTEXT.....which also means
> that it cannot sleep.   But since u know many I/O function involved
> some form of waiting, therefore printk() necessarily HAVE TO WRITE TO
> A BUFFER,
OK, I need decrease buffer depth.
Thank you.

-- 
Regards,
Alexei Babich, circuit engineer, OOO NPP "Rezonans", Chelyabinsk, Russia
http://www.rez.ru
Jabber ID: impatt@jabber.ru
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how to find when a symbol introduced into the kernel

[Zhaohui Wang]

Hi all

To write multiple kernel version compatible programs, I need to know when a specific symbol (a struct or a function)were introduced in to the kernel tree

Binary search against multiple kernel sources is a way,but is still slow.Is there any fast way to use modern git technology to make my life easier?

Many thanks.

Best Regards
Zhaohui Wang


> -----Original Message-----
> From: linux-newbie-owner@vger.kernel.org [mailto:linux-newbie-
> owner@vger.kernel.org] On Behalf Of Alexei Babich
> Sent: Friday, May 30, 2008 7:06 AM
> To: linux-newbie@vger.kernel.org
> Subject: Re:
> 
> > Check this out - since it has similar embedded requirements like
> yours
> > (what is a chematic engineer?):
> I ment circuit, not schematic, and that's a misprint in addition :)
> 
> > http://tree.celinuxforum.org/pipermail/celinux-dev/2006-
> July/001261.html
> Thank you for link.
> 
> >
> > Read the comments part of kernel/printk.c - printk() is an amazing
> > function, because it can be called in ANY CONTEXT.....which also
> means
> > that it cannot sleep.   But since u know many I/O function involved
> > some form of waiting, therefore printk() necessarily HAVE TO WRITE TO
> > A BUFFER,
> OK, I need decrease buffer depth.
> Thank you.
> 
> --
> Regards,
> Alexei Babich, circuit engineer, OOO NPP "Rezonans", Chelyabinsk,
> Russia
> http://www.rez.ru
> Jabber ID: impatt@jabber.ru
> --
> To unsubscribe from this list: send the line "unsubscribe linux-newbie"
> in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.linux-learn.org/faqs

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