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Re: [Xen-devel] Re: [PATCH] clean up CFLAGS

On 10 Mar 2006, at 08:30, Andi Kleen wrote:

The main linux kernel switched to -Os by default now. Rationale
is that for kernel code it's best to be as small in icache as possible
and the optimizations in -O2 mostly help loops etc which kernel
code doesn't tend to do a whole lot of.

Well, moving to -O2 at least looks sane. I noticed -O3 can go a bit mad with auto inlining.

On x86-64 I'm also using -fno-reorder-blocks. The main reason is that
it also makes the code a bit smaller and more important it's much easier to read the assembly code during debugging because it matches the C code

I use that flag too, mainly because I stole x86/64 Xen CFLAGS from Linux. :-)

 -- Keir

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