Re: where is ZONE_HIGHMEM defined?

["Peter Teoh" <htmldeveloper@xxxxxxxxx>]

Alternatively, you can do a "make tags" in the kernel source code
(look up Makefile, it recognize "tags" as an identifier) and the
Makefile will use ctags command to generate a "tags" file.   If u then
"vi", at the highest level in the kernel directory (purely because
make "tags" currently DOES NOT generate a "tags" file in every
subdirectory), any source code, and then put the cursor at the
beginning of the technical word u want to cross-reference, and then do
a "control-]" vi will jump directly to the file and the definition of
the identifier.   If there are multiple definition, just enter
":tnext" or ":tprev" to navigate inside the vi editor.

If I want to find out about ZONE_HIGHMEM, just create a file by any
name, put the word ZONE_HIGHMEM into the file, saved it, and then
"ctrl-]" at the beginning of the word, u will get to here:

include/linux/mmzone.h:

enum zone_type {
#ifdef CONFIG_ZONE_DMA
        /*
         * ZONE_DMA is used when there are devices that are not able
         * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
         * carve out the portion of memory that is needed for these devices.
         * The range is arch specific.
         *

         * used by i386 to allow the kernel to address the memory beyond
         * 900MB. The kernel will set up special mappings (page
         * table entries on i386) for each page that the kernel needs to
         * access.
         */
        ZONE_HIGHMEM,
#endif
        ZONE_MOVABLE,
        MAX_NR_ZONES
};

So it is just an enum :-).

On Thu, Apr 3, 2008 at 11:22 PM, Johannes Weiner <hannes@xxxxxxxxxxxx> wrote:
> Hi Robert,
>
>  "Robert P. J. Day" <rpjday@xxxxxxxxxxxxxx> writes:
>
>  > On Thu, 3 Apr 2008, Robert P. J. Day wrote:
>  >
>  >>
>  >>   i just *know* i'm going to regret asking this, but where is the
>  >> preprocessor symbol "ZONE_HIGHMEM" defined?  running the obvious
>  >> "grep" commands just isn't telling me what i want to know.  thanks.
>  >
>  > argh, never mind ... just noticed that it's defined as an enum in
>  > linux/mmzone.h.  carry on.
>
>  cscope is your friend:
>
>         $ make cscope
>         or
>         $ cscope -bkqR
>
>  to build the index and:
>
>         $ cscope -p5 -d
>
>  to start the interactive program.
>
>  `make cscope' does not include code from !YOUR_ARCH.  I don't know if it
>  does with some additional flags, so I use the second version to generate
>  the index myself.
>
>         Hannes
>
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>



-- 
Regards,
Peter Teoh

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