Re: [PATCH] unexpected IO-APIC update

["Randy.Dunlap" <rddunlap@osdl.org>]

On Tue, 24 Jun 2003 18:31:12 -0700 (PDT) Linus Torvalds <torvalds@transmeta.com> wrote:

| 
| On Tue, 24 Jun 2003, Randy.Dunlap wrote:
| >
| > +	if (reg_01.version >= 0x20)
| > +		*(int *)&reg_03 = io_apic_read(apic, 3);
| 
| There's a lot of these 
| 
| 	*(int *)&reg_03
| 
| kinds of things there, and the fact is, gcc's alias analysis doesn't like 
| them, _and_ they are ugly.
| 
[snippage]
| 
| But the ugliness part I care about, and I wonder if it wouldn't be better 
| in this case to just make the register definition a "union", and have 
| something like
| 
| 	union reg_03 {
| 		u32 value;
| 		struct {
| 			u32 boot_DT:1,
| 			    reserved:31;
| 		} bits;
| 	};
| 
| and then you can avoid the ugly dereference/cast/address-of thing, and 
| just say
| 
| 	reg_03.value
| 
| or
| 
| 	reg_03.bits.boot_DT
| 
| which looks a lot cleaner.
| 
| This is what unions are _designed_ for.

Sure, I'll do that.

--
~Randy
~ http://developer.osdl.org/rddunlap/ ~ http://www.xenotime.net/linux/ ~