Hi Sam! On Tue, Aug 09, 2016 at 12:01:08PM -0700, Sam Kumar wrote: > I noticed that there is a "oneway-malloc" module in RIOT OS. It appears to > be a thin wrapper around sbrk that only supports allocating memory, not > freeing it.
This is correct. It was originally introduced for MSP430 platforms. > I am doing some development using RIOT OS, and dynamic memory allocation > would be useful to me. Is there already a module that implements dynamic > memory allocation suitable for general-purpose use in the kernel and in > user programs? Dynamic memory allocation is usually a bad idea for embedded systems (see for instance https://www.quora.com/Why-is-malloc-harmful-in-embedded-systems). Within kernel context it MUST be completely avoided. If you really need dynamic memory allocation, you can either use the TLSF package [1] or use a simple memory manager that uses a static memory pool like memmgr [2]. TLSF is O(1), but works only on 32 bit platforms. > If such a module does not already exist, I am willing to contribute a > lightweight implementation of malloc, realloc, calloc, and free to replace > the oneway-malloc module. This could be a good idea indeed. :) I once had the above cited memmgr as package in one of my private branches, but I guess I haven't pushed it to Github. However, creating this package didn't take longer than half an hour. Cheers, Oleg [1] https://github.com/RIOT-OS/RIOT/tree/master/pkg/tlsf [2] https://github.com/eliben/code-for-blog/tree/master/2008/memmgr -- The worst thing about Perl jokes is that next morning you can't understand why they seemed so funny.
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