On Wed, 15 Aug 2007, Herbert Xu wrote:
> Andi Kleen <[email protected]> wrote:
> >> My config with march=pentium-m and gcc (GCC) 4.1.2 (Gentoo 4.1.2):
> >> text data bss dec hex filename
> >> 3434150 249176 176128 3859454 3ae3fe atomic_normal/vmlinux
> >> 3435308 249176 176128 3860612 3ae884 atomic_inlineasm/vmlinux
> >
> > What is the difference between atomic_normal and atomic_inlineasm?
>
> The inline asm stops certain optimisations from occuring.
Yup, the "__volatile__" after "__asm__" shouldn't be required. The
previous definitions allowed the compiler to optimize certain atomic
ops away, and considering we haven't seen any bugs due to the past
behaviour anyway, changing it like this sounds unnecessary.
The second behavioral change that comes about here is the force-
constraining of v->counter to memory in the extended asm's constraint
sets. But that's required to give "volatility"-like behaviour, which
I suspect is the goal of this patch.
Sebastian, could you look at the kernel images in detail and see why,
how and what in the text expanded by 1158 bytes with these changes?
> I'm still unconvinced why we need this because nobody has
> brought up any examples of kernel code that legitimately
> need this.
Me too, but I do find these more palatable than the variants using
"volatile", I admit.
Satyam
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
