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Re: Modifying bits/sched.h in eglibc source package



On Mon, Jun 27, 2011 at 08:35:41PM +0200, Miguel Telleria de Esteban wrote:
> Dear all,
> 
> I am new in this list, I am hacking around eglibc source package to
> support a change in the linux kernel ABI that I am installing on my
> local Ubuntu system.
> 
> The ABI change consists in:
> 
> *  Extending struct sched_param to support POSIX SCHED_SPORADIC
>    according to a patch proposed in the LKML:
> 
>     http://lkml.org/lkml/2008/8/11/160
> 
>    struct sched_param {
> 	int __sched_priority;
> +	int sched_ss_low_priority;
> +	struct timespec sched_ss_repl_period;
> +	struct timespec sched_ss_init_budget;
> +	int sched_ss_max_repl;
> };
> 
> 
> *  Adding a new #define SCHED_SPORADIC value of 6.
> 
> Both changes affect the installed file:
> 
>     /usr/include/bits/sched.h
> 
> However, inside the eglibc source package I find 2 instances of this
> file:
> 
>         bits/sched.h
>         sysdepends/unix/sysv/linux/bits/sched.h
> 
> MY QUESTIONS ARE:
> 
> 1. Why there are TWO files "bits/sched.h" in the source package?
>         bits/sched.h

This is for internal use when building the GNU libc.

>         sysdepends/unix/sysv/linux/bits/sched.h

This is the one installed on the system.

> 2. Is the first one (bits/sched.h) generated automatically from the
>    second (sysdepends/unix/sysv/linux/bits/sched.h)?, 
>    or
>    if we change second, can the modifications be updated in the first
>    automatically with a specific command or make rule?

No they are independent, there is no rule to build one from another.

> 3. Lots of values from these files seem to come from the kernel
>    headers, in  particular:
> 
>    /usr/src/linux-rt-headers-2.6.31-11/include/linux/sched.h 
>    (I am using linux-rt source package from Ubuntu Lucid)
>    http://packages.ubuntu.com/source/lucid-updates/linux-rt
> 
>    Is there a way to synchronize automatically eglibc headers with
>    kernel headers?
> 

No.

Aurelien

-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net


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