Re: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu area

[Mike Travis <travis@sgi.com>]

>>>>
>>>> To initialize the percpu data you do want to talk to the virtual address
>>>> at __per_coup_load.  But it is absolute Ugh. 
>>>> It might be worth saying something like.
>>>> .data.percpu.start : AT(.data.percpu.dummy - LOAD_OFFSET) {
>>>>     DATA(0)                       . = ALIGN(align);
>>>>         __per_cpu_load = . ;                   }
>>>> To make __per_cpu_load a relative symbol. ld has a bad habit of taking
>>>> symbols out of empty sections and making them absolute.  Which is why
>>>> I added the DATA(0).

The syntax error is at this "DATA(0)" statement.  I don't find this as a
linker script command or a macro.  What is it we're trying to do with this?

Thanks,
Mike
...
>>> I'm not sure I understand the linker lingo enough to fill in the rest
>>> of the blanks... I've tried various versions around this framework and
>>> none have been accepted yet.
>>>
>>> #ifdef CONFIG_HAVE_ZERO_BASED_PER_CPU
>>> #define PERCPU(align)                                                   \
>>>         .data.percpu.start : AT(.data.percpu.dummy - LOAD_OFFSET) {     \
>>>                 DATA(0)                                                 \
>>>                 . = ALIGN(align);                                       \
>>>                 __per_cpu_load = .;                                     \
>>>                 *(.data.percpu.first)                                   \
>>>                 *(.data.percpu.shared_aligned)                          \
>>>                 *(.data.percpu)                                         \
>>>                 *(.data.percpu.page_aligned)                            \
>>>                 ____per_cpu_size = . - __per_cpu_load                   \
>>>         }                                                               \
>>> #else