Paul Menage wrote:
> On Tue, Nov 9, 2010 at 4:52 PM, Li Zefan <lizf@xxxxxxxxxxxxxx> wrote:
>>> bool active:1;
>>> bool disabled:1;
>>>
>> It won't compile, but unsigned char active:1 will do. ;)
>
> Are you sure? I don't have a buildable kernel tree at the moment, but
> the following fragment compiled fine for me (with gcc 4.4.3):
>
> struct foo {
> _Bool b1:1;
> _Bool b2:1;
> };
>
> and was sized at one byte. And "bool" is just a typedef of _Bool in
> the kernel headers.
>
Oops, I just used bool outside kernel tree..
>> Every thing that reduces code size (without sacrifice readability
>> and maintain maintainability) should be worth.
>
> Agreed, within reason. But this patch doesn't reduce code size - it
I meant binary size.
> makes the code fractionally more complicated and reduces the *binary*
> size by a few bytes.
>
It's a commonly used skill in kernel code, so I can't say it makes
code more complicated.
That said, I'll happily drop this patch. It just came to me when I
started to add new bool values to the structure. Or if you prefer
bool xxx:1 or just bool xxx, I can do that.
>> This is one of the reasons we accept patches that replacing
>> kmalloc+memset with kzalloc, which just saves 8 bytes in my box.
>>
>
> Replacing two function calls with one function call is a code
> simplification and hence (generally) a good thing - the minuscule
> reduction in binary size reduction that comes with it is just noise.
>
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