Zack, did you ever make any progress on this? I'm just looking at tickets and wondered.
On Sat, Dec 11, 2021 at 9:41 AM Gedare Bloom <ged...@rtems.org> wrote: > > On Thu, Nov 18, 2021 at 7:22 PM zack leung <zakthertems...@gmail.com> wrote: > > > > bump > > > > On Mon, 18 Oct 2021 at 23:58, zack leung <zakthertems...@gmail.com> wrote: > > > > > bump > > > > > > > > > On Sat, 25 Sept 2021 at 00:26, zack leung <zakthertems...@gmail.com> > > > wrote: > > > > > >> bump > > >> > > >> On Thu, 9 Sept 2021 at 02:17, zack leung <zakthertems...@gmail.com> > > >> wrote: > > >> > > >>> >Thanks! I guess i'm really unsure about how the pointer relates to the > > >>> amount of memory that you can use. I assume the Malloc keeps track of > > >>> the > > >>> sections being used in the heap. Does this function Allocate 2 blocks > > >>> since > > >>> the pointer is set to > > >>> > > >>> (uintptr_t) next_block + HEAP_ALLOC_BONUS - alloc_begin; > > >>> > > No, this is calculating the size of 'this block' considering that it's > allocated memory starts at "alloc_begin" and it ends at the > "next_block" heap block metadata or header. You should read about how > malloc implementations generally work. The allocated memory has some > metadata before it to implement the linked data structures necessary > to support dynamic allocation. So a block is the header + allocated > range. Only the allocated range plus any excess before the next > block's header is considered usable. > > > >>> >(I know it's a bit naive to assume this given my first question) > > >>> > > >>> think the method is _Heap_Size_of_alloc_area. It may need a wrapper > > >>> added to the protected heap wrapper for safety. I don't know if it has > > >>> one. > > >>> It should be the equivalent functionality. > > >>> > How would i implement a wrapper and what safety measures need to be > > >>> implemented. So far it's checking if : the block is not in the heap > > >>> and if > > >>> it's been previously used. Is the usable memory in the heap calculated > > >>> by: > > >>> the size of the block * # of blocks? > > >>> > > You would have to see if the Protected Heap implementation has some > additional metadata between the end of an allocated range in one block > and the block header in the next. I don't think it matters too much > because most of the 'protected' aspects have to do with free block > management. But that should be confirmed. > > The check is not "if it's been previously used" I suggest that you > look at what the invoked function does and how it is documented. Avoid > making assumptions based on names. > > The usable memory is NOT the size of the block * # of blocks, because > the size of the block includes the header. > > > >>> Thanks, Zack > > >>> > > >>> ---------- Forwarded message --------- > > >>> From: Joel Sherrill <j...@rtems.org> > > >>> Date: Wed, 8 Sept 2021 at 20:30 > > >>> Subject: Re: Ticket 4503 > > >>> To: Gedare Bloom <ged...@rtems.org> > > >>> Cc: zack leung <zakthertems...@gmail.com>, rtems-de...@rtems.org < > > >>> devel@rtems.org> > > >>> > > >>> > > >>> > > >>> > > >>> On Wed, Sep 8, 2021 at 11:02 AM Gedare Bloom <ged...@rtems.org> wrote: > > >>> > > >>>> Hi Zack, > > >>>> > > >>>> https://devel.rtems.org/ticket/4503 > > >>>> > > >>>> The malloc implementation exists in the score as the Heap Manager. > > >>>> search for "Heap_" within cpukit to get some ideas where to look. > > >>>> > > >>> > > >>> I think the method is _Heap_Size_of_alloc_area. It may need a wrapper > > >>> added to the protected heap wrapper for safety. I don't know if it has > > >>> one. > > >>> It should be the equivalent functionality. > > >>> > > >>> newlib's malloc.h will need looking at to make sure we provide the right > > >>> methods. > > >>> > > >>> > > >>> > > >>>> > > >>>> @Joel are these two tickets duplicates? > > >>>> https://devel.rtems.org/ticket/4503 > > >>>> https://devel.rtems.org/ticket/4271 > > >>>> > > >>> > > >>> Yes. Closed #4271 and merged comments. > > >>> > > >>> --joel > > >>> > > >>> > > >>>> > > >>>> > > >>>> -Gedare > > >>>> > > >>>> On Tue, Sep 7, 2021 at 7:14 PM zack leung <zakthertems...@gmail.com> > > >>>> wrote: > > >>>> > > >>>>> I was wondering about ticket 4503. I was wondering where The required > > >>>>> functionality should be in the underlying score/ capability used can > > >>>>> be > > >>>>> found to write this function. Also how does this relate to > > >>>>> > > >>>>> Add common malloc family extension method malloc_usable_size() > > >>>>> <https://devel.rtems.org/ticket/4271>? > > >>>>> Thanks > > >>>>> Zack > > >>>>> _______________________________________________ > > >>>>> devel mailing list > > >>>>> devel@rtems.org > > >>>>> http://lists.rtems.org/mailman/listinfo/devel > > >>>> > > >>>> > > _______________________________________________ > > devel mailing list > > devel@rtems.org > > http://lists.rtems.org/mailman/listinfo/devel > _______________________________________________ > devel mailing list > devel@rtems.org > http://lists.rtems.org/mailman/listinfo/devel _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
