Hi Guenter, Russell, On Tue, 27 Aug 2013 06:37:27 -0700, Guenter Roeck wrote: > On 08/27/2013 04:30 AM, Russell King - ARM Linux wrote: > > On Tue, Aug 27, 2013 at 01:14:58PM +0200, Jean Delvare wrote: > >> Russell, can you explain? Is this an old gcc misbehavior which has been > >> fixed meanwhile, or...? > >> > >> Me, I can't see how a section attribute could apply to a variable type > >> in the first place, so I'd expect gcc to either transparently apply it > >> to the variable instead (which it apparently does for me) or emit a > >> warning. > >> > >> OTOH if the problem is real then a check for it should be added to > >> checkpatch.pl because I don't think a lot of people know about it. A > >> quick grep suggests that 29% of the use cases (1260 occurrences) have > >> it wrong. > > > > If it's gcc misbehaviour, then it's documented gcc misbehaviour, because > > my description in the above link comes from the GCC info pages. See: > > > > C Extensions -> Attribute Syntax > > > > This is because attributes can be either function attributes, variable > > attributes or type attributes. Which kind they are depends on where > > they are placed. > > > > When they are placed immediately after 'struct', 'enum' or 'union', or > > immediately after the closing brace of such a declaration, they are a > > type attribute. It may be possible to argue that a section-specifying > > attribute should be allowable as part of the type, but that doesn't > > appear to be the case (and it doesn't error out either.) > > > > The version online at: http://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html > > looks very similar to the version I've been reading for my gcc version, > > so I assume nothing has changed in this regard. > > > > If I understand the document correctly, > static struct dmi_system_id __initdata pm_dmi_table[] = { > applies the attribute to the type used to declare the variable, > thus the variable will be of type 'struct dmi_system_id __initdata' > and be placed in initdata. > > static struct dmi_system_id pm_dmi_table[] __initdata = { > applies the attribute to the variable, with the same result. Not even sure, as http://gcc.gnu.org/onlinedocs/gcc/Type-Attributes.html#Type-Attributes doesn't list "section" as a valid attribute for types. > So I wonder - is this a real problem ? The result should be the same > in either case. I think that what applies here is this little note at the end of the "Attribute Syntax" documentation: "If an attribute that only applies to declarations is applied to the type of a declaration, it will be treated as applying to that declaration." I believe this is exactly what I'm seeing in my tests. Also note that the fix Sachin sent for acpi_power_meter is slightly different from what Russell complained about originally. Russell complained about: struct __initdata foo bar; While acpi_power_meter uses: struct foo __initdata bar; The former does indeed NOT work in my tests, so Russell was right complaining. The good news is that there are only a few dozen occurrences of this in the kernel tree. The later OTOH works fine in my tests so I see no reason to change it - unless someone can find a gcc version and platform combination where it does not work. Hope this clarifies the whole situation... -- Jean Delvare _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
