In a 2.4 kernel, mm/page_alloc.c:free_area_init_core(), in the following
assignement...
bitmap_size = size >> i;
...makes bitmap_size be the double of the needed size, this calculum
assumes that with a 512 byte map size the kernel is mapping 8*512= 4096 chunks
of memory, that is: one bit of the map is used for each chunk of memory,
and that's not true.
Really one bit of area->map is used to map two chunks of memory, so in the
example above an area->map of just 256 bytes is really needed, the other 256
bytes are _never accessed_.
So the righ thing would be to do is:
bitmap_size = size >> (i+1);
also I tested it and it works ok, so I believe I'm right...
Please CC: your replies to (I'm not subscribed to this list)
Ulisses Alonso Camaró <uaca@NOSPAM.alumni.uv.es>
PD: my nick on #kernelnewbies is despistao
Debian GNU/Linux: a dream come true
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