Re: [PATCH] x86: tell the world boot_params is 16-byte aligned

From: Rasmus Villemoes
Date: Fri May 08 2015 - 12:24:03 EST

On Fri, May 08 2015, Borislav Petkov <bp@xxxxxxxxx> wrote:

> On Fri, May 08, 2015 at 03:42:33PM +0200, Rasmus Villemoes wrote:
>> It doesn't matter much, but this disassembly makes me cry a little bit:
>> ffffffff81f21223 <copy_bootdata>:
>> ffffffff81f21223: 55 push %rbp
>> ffffffff81f21224: 48 c7 c0 40 c2 02 82 mov $0xffffffff8202c240,%rax
>> ffffffff81f2122b: 48 89 fe mov %rdi,%rsi
>> ffffffff81f2122e: a8 01 test $0x1,%al
>> The reason is that boot_params is defined with
>> __attribute__((aligned(16))) in boot/main.c, but other translation
>> units only see the packed attribute on the definition of struct
>> boot_params, so assume the worst. Making the de facto alignment public
> Wouldn't it be better if we put both attributes together, i.e.:

Sure, putting it on the type works as well. Either way is fine with me.

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