MB2PAGES
if (realmem < MB2PAGES(128))
min_pages = MB2PAGES(8) + (realmem >> 1);
else if (realmem < MB2PAGES(512))
min_pages = MB2PAGES(40) + (realmem >> 2);
else if (realmem < MB2PAGES(2048))
min_pages = MB2PAGES(104) + (realmem >> 3);
min_pages = MB2PAGES(296) + (realmem >> 5);