Re: [gentoo-server] linux-headers: insanity? WAS: linux-headers update?

[Marius Mauch]

[EMAIL PROTECTED] wrote:
In a LKML post [1] about the symlinking of /usr/include/linux to 
/usr/src/linux/include/ which has been done for quite some time in older 
Linux distributions, Linus calls doing this "instanity" and states that 
the kernel headers used to compile glibc and friends should always be 
taken from the glibc distribution (which includes a patched set of 
kernel headers) and one should not use the headers from the kernel.org 
tarball.
You misread what he said (see below).
But this is exactly what Gentoos linux-headers package does: get the 
kernel tarball and install the required files. The result is in effect 
not really different from the old symlinking method.
It is.
Now am I misreading Linus' recommendation?
When he sais:
Basically, that symlink should not be a symlink. It's a symlink for 
historical reasons, none of them very good any more (and haven't been 
for a long time), and it's a disaster unless you want to be a C 
library developer. Which not very many people want to be.

The fact is, that the header files should match the library you link 
against, not the kernel you run on.
That's the important sentence.
and later:
[...] you should not use the kernel headers: You should use the 
headers that glibc came with. It is probably a Red Hat bug that those 
headers were a symbolic link.

Does that mean:
a) glibc comes with patched kernel headers that should always be used 
when compiling other applications/libs
or
b) it doesn't matter what kernel headers you use to build your glibc 
with as long as any apps that use glibc use the very same headers at 
compile time.
b)
The point is that all libraries/applications should use the same 
headers. When you make a symlink the headers are changed on every kernel 
upgrade, so applications using those headers (in theory only glibc and 
kernel related applications should directly use those headers, but lets 
ignore that for now) might have a different idea about data structures 
than glibc, and that can result in very weird (and possibly serious) 
problems.

Marius
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