The kernel and the C library as a single project [LWN.net]

The kernel and the C library as a single project

Posted Nov 30, 2010 20:46 UTC (Tue) by pj (subscriber, #4506)
Parent article: The kernel and the C library as a single project

How about some middle ground... making syscall() less fiddly and more architecture-portable somehow (export a map of name -> syscall numbers into /sys/kernel somewhere, for instance) so that it was an actual option might be enough.

Pulling all of libc into the kernel strikes me as... bad. Compare the size of glibc to uclibc or eglibc ... the mere existence of all of them means to me that options are desirable.

So... maybe a kernel module? To try out the idea, at least. Ship it with a stub userland libc to link against, or patch an existing libc to detect it and use it if found.

We had an http server kernel module for some years (is that still maintained, even out of tree?), why not a libc one?

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The kernel and the C library as a single project

Posted Nov 30, 2010 21:06 UTC (Tue) by signbit (guest, #71372) [Link] (4 responses)

I won't be libc in the kernel runtime but libc in the kernel source code repository. It will still go in /lib/libc.so.$WHATEVER.

What happened to klibc? Wasn't that supposed to stay close and true to the kernel?

The kernel and the C library as a single project

Posted Nov 30, 2010 21:31 UTC (Tue) by johill (subscriber, #25196) [Link] (1 responses)

libc could be a VDSO I guess ...

The kernel and the C library as a single project

Posted Dec 1, 2010 8:14 UTC (Wed) by smueller@atsec.com (guest, #68260) [Link]

Considering how vDSO is implemented, why not exporting all system calls as stubs in the vDSO part? This way, user space could simply link to that vDSO AND use the system calls like a normal API without going through the oddities of syscall()?

klibc is direct opposite

Posted Nov 30, 2010 22:27 UTC (Tue) by khim (subscriber, #9252) [Link]

Klibc is alive and well - but it's direct opposite to what's offered! Klibc is minimalistic libc - enough to run initscripts, certainly now enough to run heavy-duty apps! It offers access to very few syscalls (you don't need much to insmod some modules and create few /dev files) and does not follow "latest and greatest" changes in kernel at all.

The kernel and the C library as a single project

Posted Dec 1, 2010 6:14 UTC (Wed) by jamesh (guest, #1159) [Link]

The quote from Ingo talks of making it a VDSO. That is, code mapped into the address space of every new process by the kernel, rather than libraries loaded from the file system by the dynamic linker.