PATCH: mount -O list

Denys Vlasenko vda.linux at googlemail.com
Fri Dec 4 14:43:04 UTC 2009


On Fri, Dec 4, 2009 at 2:06 PM, Michael Abbott <michael at araneidae.co.uk> wrote:
> On Fri, 4 Dec 2009, Denys Vlasenko wrote:
>> On Fri, Dec 4, 2009 at 1:48 PM, Michael Abbott <michael at araneidae.co.uk> wrote:
>> > On Fri, 4 Dec 2009, walter harms wrote:
>> >> Michael Abbott schrieb:
>> >> > 3. strchrnul() -- oh, that is nice!  Is that a busybox special function?
>> >> > It doesn't seem to be part of glibc.  Of course, makes the step on to the
>> >> > next item at the end of the loop slightly more clunky.
>> On the contrary, it makes the step smaller. I checked code size.
>
> Intruiging.
>
> I was only referring to the difference between
>        if (!O_comma)
>                break;
> and
>        if (O_opt[O_len] == '\0')
>                break;
> and now think I was talking nonsense, each is as clear as each other.  Of
> course the first is (potentially) just a register access, while the second
> definitely fetches ram

For that, O_comma needs to survive in register through two nested loops.
Not likely, unless your CPU has 64+ registers. gcc spills it into a stack slot.
--
vda


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