In my case I define in the linkerscript all regions that "I will ever need", so they are always there. The startup code can always find the predetermined symbols.
If I don't use a region, I set it to DONT_LINK. Since it's size will be 0, the start up code will ignore it. I know, it's not the most elegant solution, but it's simple and working. I cannot image a system with 50 different heap regions, so it doesn't need to scale. Alternatively, the number (or names) of regions can be a Make.defs list. Every board has a Make.defs that defines the platform specifics, so it's a good candidate IMO. (I think I have done this in the past in a similar way, but I don't have access to this code anymore). On Fri, Mar 26, 2021, 20:56 Xiang Xiao <xiaoxiang781...@gmail.com> wrote: > Fotis, you define many symbols(e.g. __gp_ram?_bss_start__) in your linker > script. My question is how the common init code knows the number of these > symbols? > > On Fri, Mar 26, 2021 at 9:46 AM Fotis Panagiotopoulos <f.j.pa...@gmail.com > > > wrote: > > > Oh, sorry. > > Attached again as .txt. Is it OK now? > > > > > A tool that takes the Kconfig + chip+ memorymap and make a linker > include > > > file and the config code for the heap may be the way to go. > > > > I am pretty sure that a "tool" will not be able to cover all use cases. > > Over the years I had to make custom scripts to account for: > > * Bootloaders > > * Binary blops > > * Firmware headers > > * ROM files > > * DMA buffers > > * External memories > > etc etc.. > > > > Do you believe that a tool can be made that can handle everything? > > > > > > Στις Παρ, 26 Μαρ 2021 στις 6:37 μ.μ., ο/η David Sidrane < > > david.sidr...@nscdg.com> έγραψε: > > > >> I am just thinking out load... > >> > >> I agree this has to come from one place. But I do think it is just the > >> linker file. > >> > >> Currently we have > >> The arch memroymap h files have the base addresses, sizes - This is the > >> Reference manuals counterpart, it covers all the sub members of the > chips) > >> The chip.h files that has sizes - This is the Data Sheet counterpart, > it > >> covers one or more of the sub members of the chips) > >> The Kconfig - More flexible from a users stand point. > >> The heap c files - buried semantics - not good > >> linker file - the boards usage specific. > >> > >> I like using the linker file, but Kconfig is build time - no file > >> modification > >> > >> Just moving things to the linker file does not fix the ordering or > adding > >> issues. (it is link time not compile time) > >> > >> A tool that takes the Kconfig + chip+ memorymap and make a linker > include > >> file and the config code for the heap may be the way to go. > >> > >> David > >> > >> > >> -----Original Message----- > >> From: Fotis Panagiotopoulos [mailto:f.j.pa...@gmail.com] > >> Sent: Friday, March 26, 2021 9:17 AM > >> To: dev@nuttx.apache.org > >> Subject: Re: How to ensure HEAP will not overlap static DMA buffer? > >> > >> I face similar problems (with a different use case) on an STM32F4. > >> The thing is that although the linker script belongs to the board logic > >> and > >> thus it is freely customizable, the heap regions are hard-coded in the > >> arch > >> files. > >> > >> So, I started working on PR #2277 ( > >> https://github.com/apache/incubator-nuttx/pull/2277), but > unfortunately I > >> had to pause the development on this. > >> The idea is similar to what you describe here. Everything can be defined > >> in > >> the linkerscript (addresses, order, sizeses etc). > >> > >> I was thinking a lot of any alternatives on this. I came to the > conclusion > >> that Kconfig is the wrong tool for this job. > >> You lose all compile-time (and CI) checks and can easily be > misconfigured. > >> I am also afraid that we will end up with a few dozen "hacks" like above > >> or > >> like STM32_CCMEXCLUDE (I never liked this option....). > >> And no matter what you do, you will never be able to satisfy any crazy > >> memory mappings that any project may need. > >> > >> A similar issue to this is Issue #2001 ( > >> https://github.com/apache/incubator-nuttx/issues/2001). > >> This was my first crash while trying out NuttX :) > >> In short, there is the assumption that the main stack will always reside > >> between BSS and Heap, again being very restrictive. > >> > >> > >> Στις Παρ, 26 Μαρ 2021 στις 5:46 μ.μ., ο/η Nathan Hartman < > >> hartman.nat...@gmail.com> έγραψε: > >> > >> > On Fri, Mar 26, 2021 at 11:41 AM Gregory Nutt <spudan...@gmail.com> > >> wrote: > >> > > >> > > Missing bit of logic: > >> > > > >> > > >> Speaking of the linker, is there a way to use a combination of > the > >> > > >> linker script and __attribute__ incantations in the code to > detect > >> > > >> automatically the size that g_sram4_reserve should be and > entirely > >> > > >> eliminate the need for the user to specify the start and end of > >> each > >> > > >> region in Kconfig? > >> > > > > >> > > > Are you thinking of something like this in the linker script: > >> > > > > >> > > > .sram4_reserve : > >> > > > { > >> > > > _sram4_reserve_begin = ABSOLUTE(.); > >> > > > *(.sram4) > >> > > > _sram4_reserve_end = ABSOLUTE(.); > >> > > > } > >> > > > > >> > > > And in the C code: > >> > > > > >> > > We need to lie to C and tell it what to think those symbols are: > >> > > > >> > > EXTERN const uint32_t _sram4_reserve_begin > >> > > EXTERN const uint32_t _sram4_reserve_begin > >> > > >> > > >> > > >> > Ah, yes, otherwise those symbols would be undefined. Later the linker > >> will > >> > resolve them to the correct addresses. > >> > > >> > > >> > > #define SRAM4_RESERVE_BEGIN &_sram4_reserve_begin > >> > > > #define SRAM4_RESERVE_END &_sram4_reserve_end > >> > > > > >> > > > The implied size depends on the size of all .sram4 sections. I > >> assume > >> > > > this would be positioned at the beginning of SRAM4 and the size of > >> the > >> > > > region that could be added to the heap would be SRAM4_RESERVE_END > >> > > > through SRAM_END. > >> > > > > >> > > You can see this same kind of thing in, for example, > >> > > arch/arm/src/common/arm_internal.h > >> > > >> > > >> > > >> > Great! Thanks > >> > > >> > Nathan > >> > > >> > > >
