u-boot/include/malloc.h

190      Define this on MS win (95, nt) platforms to compile in sbrk emulation.
195   MORECORE                  (default: sbrk)
201      holds for sbrk).
207      controlling interaction with host system routines (sbrk, mmap, etc).
315   WIN32 causes an emulation of sbrk to be compiled in
329   Microsoft Visual C++ data structures and routines used in the 'sbrk'
640       Because trimming via sbrk can be slow on some systems, and can
672       sbrk, mmap, and munmap otherwise degrade performance, the default
691       retain whenever sbrk is called. It is used in two ways internally:
693       * When sbrk is called to extend the top of the arena to satisfy
694 	a new malloc request, this much padding is added to the sbrk
703       The main reason for using padding is to avoid calling sbrk so
706       after trimming) will invoke sbrk, which needlessly wastes
711       systems where sbrk is relatively slow, it can pay to increase
778 	    better off using normal sbrk-based allocation routines that
841 extern Void_t*     sbrk(ptrdiff_t);
843 extern Void_t*     sbrk();
847 #define MORECORE sbrk