Messages in this thread | | | Date | Mon, 22 Nov 2004 13:46:18 +0100 | From | Adrian Bunk <> | Subject | Re: [2.6 patch] Use -ffreestanding? (fwd) |
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On Sun, Nov 21, 2004 at 10:10:28PM -0800, Linus Torvalds wrote: > > > On Mon, 22 Nov 2004, Adrian Bunk wrote: > > > > for the kernel, it would be logical to use -ffreestanding. The kernel is > > not a hosted environment with a standard C library. > > > > Linus agreed that it would make sense. > > Note that while I agree that it sounds sensible, it would be good to have > somebody specify exactly what changes from the use of "-ffreestanding". > > I _assume_ that all the things that gcc takes for granted are things that > Linux already has its own definitions for, and that -ffreestanding doesn't > actually change anything for at least the regular architectures. But if > there is any object code changes, can you check those out and explain > them?
Andi Kleen reported: Newer gcc rewrites sprintf(buf,"%s",str) to strcpy(buf,str) transparently.
This is only true with unit-at-a-time (disabled on i386 but enabled on x86_64). The Linux kernel doesn't offer a standard C library, and such transparent replacements of kernel functions with builtins are quite fragile.
Even with -ffreestanding, it's still possilble to explicitely use a gcc builtin if desired.
> Linus
cu Adrian
--
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