[gentoo-user] linux-headers-2.6.38

[gentoo-user] linux-headers-2.6.38

[Pandu Poluan]

While I'm about to do an `emerge -e @world` ...

Should I `emerge -av "=sys-kernel/linux-headers-2.6.38" ` ?

Any benefits over the current "sys-kernel/linux-headers-2.6.36.1" ?

Rgds,
-- 
Pandu E Poluan
~ IT Optimizer ~

 • Blog : http://pepoluan.tumblr.com
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[gentoo-user] Re: linux-headers-2.6.38

[che]

Pandu Poluan <pandu@poluan.info> writes:

> While I'm about to do an `emerge -e @world` ...
>
> Should I `emerge -av "=sys-kernel/linux-headers-2.6.38" ` ?
>
> Any benefits over the current "sys-kernel/linux-headers-2.6.36.1" ?

There is at least a theoretical benifit if you set NPTL_KERN_VER=2.6.38
in make.conf and recompile glibc. That way glibc could use things not
present in older kernels.

I haven't researched if there are any such things, perhaps someone else
knows.

Also, beware. If you recompile glibc withe NPTL_KERN_VER set, you can't
boot with older kernels anymore.

--
 Christer

Re: [gentoo-user] Re: linux-headers-2.6.38

[Pandu Poluan]

On Wed, Aug 10, 2011 at 20:02,  <che@chrekh.se> wrote:
> Pandu Poluan <pandu@poluan.info> writes:
>
>> While I'm about to do an `emerge -e @world` ...
>>
>> Should I `emerge -av "=sys-kernel/linux-headers-2.6.38" ` ?
>>
>> Any benefits over the current "sys-kernel/linux-headers-2.6.36.1" ?
>
> There is at least a theoretical benifit if you set NPTL_KERN_VER=2.6.38
> in make.conf and recompile glibc. That way glibc could use things not
> present in older kernels.
>
> I haven't researched if there are any such things, perhaps someone else
> knows.
>

Hmmm... without a reference, I'd rather not do something too drastic...

> Also, beware. If you recompile glibc withe NPTL_KERN_VER set, you can't
> boot with older kernels anymore.
>

Can you explain what did you mean with "older kernels"? Kernels older
than a certain version, or a previously-compiled kernel on my system?

Anyways, this is a fresh install, so I don't think I'll have any trouble.

But will still appreciate a reference and/or explanation re:
NPTL_KERN_VER, though.

Rgds
-- 
FdS Pandu E Poluan
~ IT Optimizer ~

 • Blog : http://pepoluan.tumblr.com
 • Linked-In : http://id.linkedin.com/in/pepoluan

[gentoo-user] Re: linux-headers-2.6.38

[che]

Pandu Poluan <pandu@poluan.info> writes:
> On Wed, Aug 10, 2011 at 20:02,  <che@chrekh.se> wrote:
>> Also, beware. If you recompile glibc withe NPTL_KERN_VER set, you can't
>> boot with older kernels anymore.
>>
>
> Can you explain what did you mean with "older kernels"? Kernels older
> than a certain version, or a previously-compiled kernel on my system?
>

Older then the kernel you specified, previously-compiled kernels not
older than that is still fine.

Any executable linked to glibc will fail unconditionally with
"FATAL: Kernel too old", including init.


> Anyways, this is a fresh install, so I don't think I'll have any trouble.
>
> But will still appreciate a reference and/or explanation re:
> NPTL_KERN_VER, though.

glibc will be configured with --enable-kernel=2.6.38

The configure help says this;

 --enable-kernel=VERSION compile for compatibility with kernel not older than VERSION

--
 Christer

[gentoo-user] Re: linux-headers-2.6.38

[Nikos Chantziaras]

On 08/10/2011 04:02 PM, che@chrekh.se wrote:
> Pandu Poluan<pandu@poluan.info>  writes:
>
>> While I'm about to do an `emerge -e @world` ...
>>
>> Should I `emerge -av "=sys-kernel/linux-headers-2.6.38" ` ?
>>
>> Any benefits over the current "sys-kernel/linux-headers-2.6.36.1" ?
>
> There is at least a theoretical benifit if you set NPTL_KERN_VER=2.6.38
> in make.conf and recompile glibc. That way glibc could use things not
> present in older kernels.
>
> I haven't researched if there are any such things, perhaps someone else
> knows.

glibc will use things in newer kernels anyway.  You don't need to use 
NPTL_KERN_VER=2.6.38 in order for glibc to use 2.6.38 features; it will 
do that by default.  NPTL_KERN_VER only omits fallbacks for older 
kernels.  It's there to reduce the size of glibc.  The size difference 
is very small though.

Re: [gentoo-user] Re: linux-headers-2.6.38

[Pandu Poluan]

On Thu, Aug 11, 2011 at 07:50, Nikos Chantziaras <realnc@arcor.de> wrote:
> On 08/10/2011 04:02 PM, che@chrekh.se wrote:
>>
>> There is at least a theoretical benifit if you set NPTL_KERN_VER=2.6.38
>> in make.conf and recompile glibc. That way glibc could use things not
>> present in older kernels.
>
> glibc will use things in newer kernels anyway.  You don't need to use
> NPTL_KERN_VER=2.6.38 in order for glibc to use 2.6.38 features; it will do
> that by default.  NPTL_KERN_VER only omits fallbacks for older kernels.
>  It's there to reduce the size of glibc.  The size difference is very small
> though.
>

Thanks for the explanation, Nikos. Since the size difference is very
small, I'll just use NPTL_KER_VER as it is (that is, not mucking with
it).

Rgds,
-- 
FdS Pandu E Poluan
~ IT Optimizer ~

 • Blog : http://pepoluan.tumblr.com
 • Linked-In : http://id.linkedin.com/in/pepoluan

[gentoo-user] Re: linux-headers-2.6.38

[che]

Nikos Chantziaras <realnc@arcor.de> writes:

>
> glibc will use things in newer kernels anyway.  You don't need to use
> NPTL_KERN_VER=2.6.38 in order for glibc to use 2.6.38 features; it
> will do that by default.  NPTL_KERN_VER only omits fallbacks for older
> kernels.  It's there to reduce the size of glibc.  The size difference
> is very small though.

That seems likely. Thanks.

Do you know if linux-headers-2.6.38 is needed for that to work?

I would guess it is.


--
 Christer