[TESTING]: one more boot2 shrinking patch

John Baldwin jhb at freebsd.org
Thu Mar 10 15:23:16 UTC 2011

On Wednesday, March 09, 2011 6:24:36 pm Dimitry Andric wrote:
> On 2011-03-09 14:23, John Baldwin wrote:
> >> gcc nor clang emits any code to initialize static type foo = 0;
> >> because it's expected that BSS is zeroed, which is not the case
> >> in boot2 so we have to initialize that explicitly
> > It used to be that if you explicitly initialized a variable to 0, it was
> > initialized to 0 in .data, but now gcc and clang recognize it is set to 0 and
> > move it to .bss.  There appears to be no way to turn this feature off,
> Yes, there is; both gcc and clang have this option to turn it off:
> -fno-zero-initialized-in-bss
>      If the target supports a BSS section, GCC by default puts variables
>      that are initialized to zero into BSS. This can save space in the
>      resulting code.
>      This option turns off this behavior because some programs
>      explicitly rely on variables going to the data section. E.g., so
>      that the resulting executable can find the beginning of that
>      section and/or make assumptions based on that.
>      The default is -fzero-initialized-in-bss.

Hah, that is better then.  Thanks! I should have searched about this more
myself. :(  Roman, can you try reverting the kname changes and adding this
to CFLAGS instead for both compilers?

John Baldwin

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