Risc-v memory issue
Denis Obrezkov
denisobrezkov at gmail.com
Wed Jun 14 05:42:56 UTC 2017
2017-06-14 8:35 GMT+03:00 Hesham Almatary <heshamelmatary at gmail.com>:
> On Wed, Jun 14, 2017 at 2:58 PM, Denis Obrezkov <denisobrezkov at gmail.com>
> wrote:
> > 2017-06-14 2:18 GMT+03:00 Hesham Almatary <heshamelmatary at gmail.com>:
> >>
> >>
> >>
> >> On Tue, Jun 13, 2017 at 10:20 PM, Joel Sherrill <joel at rtems.org> wrote:
> >>>
> >>>
> >>>
> >>> On Jun 12, 2017 3:10 PM, "Hesham Almatary" <heshamelmatary at gmail.com>
> >>> wrote:
> >>>
> >>>
> >>>
> >>> On Tue, Jun 13, 2017 at 2:09 AM, Denis Obrezkov <
> denisobrezkov at gmail.com>
> >>> wrote:
> >>> > Hello all,
> >>> >
> >>> > I was able to debug my program on top of HiFive1 board.
> >>> > I found out that I can't use next and until commands from gdb,
> >>> > they just hang gdb.
> >>> > And now I have a problem, this is my backtrace:
> >>> >
> >>> > #0 0x2041d728 in _User_extensions_Iterate (arg=0x80002eb8,
> >>> > visitor=0x2041d64e <_User_extensions_Fatal_visitor>,
> >>> > direction=CHAIN_ITERATOR_FORWARD)
> >>> > at
> >>> >
> >>> > /home/reprofy/Projects/riscv/rtems/development/rtems/
> kernel/rtems-riscv/c/src/../../cpukit/score/src/userextiterate.c:155
> >>> > #1 0x20410ed4 in _User_extensions_Fatal (source=INTERNAL_ERROR_CORE,
> >>> > error=2) at
> >>> > ../../cpukit/../../../hifive1/lib/include/rtems/score/
> userextimpl.h:307
> >>> > #2 0x20410ef8 in _Terminate (the_source=INTERNAL_ERROR_CORE,
> >>> > the_error=2)
> >>> > at
> >>> >
> >>> > /home/reprofy/Projects/riscv/rtems/development/rtems/
> kernel/rtems-riscv/c/src/../../cpukit/score/src/interr.c:35
> >>> > #3 0x20410f40 in _Internal_error
> >>> > (core_error=INTERNAL_ERROR_TOO_LITTLE_WORKSPACE) at
> >>> >
> >>> > /home/reprofy/Projects/riscv/rtems/development/rtems/
> kernel/rtems-riscv/c/src/../../cpukit/score/src/interr.c:44
> >>> > #4 0x2041e484 in _Workspace_Handler_initialization
> (areas=0x80002f78,
> >>> > area_count=1, extend=0x0) at
> >>> >
> >>> > /home/reprofy/Projects/riscv/rtems/development/rtems/
> kernel/rtems-riscv/c/src/../../cpukit/score/src/wkspace.c:123
> >>> > #5 0x2040031c in bsp_work_area_initialize_default
> >>> > (area_begin=0x80001d58,
> >>> > area_size=8872) at
> >>> > ../../../../../.././hifive1/lib/include/bsp/bootcard.h:147
> >>> > #6 0x20400372 in bsp_work_area_initialize () at
> >>> >
> >>> > /home/reprofy/Projects/riscv/rtems/development/rtems/
> kernel/rtems-riscv/c/src/lib/libbsp/riscv32/hifive1/../../
> shared/bspgetworkarea.c:61
> >>> > #7 0x2040f3ce in rtems_initialize_executive () at
> >>> >
> >>> > /home/reprofy/Projects/riscv/rtems/development/rtems/
> kernel/rtems-riscv/c/src/../../cpukit/sapi/src/exinit.c:95
> >>> > #8 0x204002cc in boot_card (cmdline=0x0) at
> >>> >
> >>> > /home/reprofy/Projects/riscv/rtems/development/rtems/
> kernel/rtems-riscv/c/src/lib/libbsp/riscv32/hifive1/../../
> shared/bootcard.c:76
> >>> > #9 0x20400064 in _end_clear_bss () at
> >>> >
> >>> > /home/reprofy/Projects/riscv/rtems/development/rtems/
> kernel/rtems-riscv/c/src/lib/libbsp/riscv32/hifive1/start/start.S:116
> >>> >
> >>> > So, I think I should increase a workspace.
> >>> > Now, I have some questions:
> >>> > I took Hesham's linker file for riscv-generic, and there were no
> stack
> >>> > space,
> >>> > I allocated 0x1000 for stack. Should I make it zero again, or should
> I
> >>> > decrease its size?
> >>> > what size for stack should be enough?
> >>>>
> >>>> /*
> >>>> * The stack section will occupy the remaining
> >>>> REGION_STACK region and may
> >>>> * contain the task stacks. Depending on the region
> >>>> distribution this
> >>>> * section may be of zero size.
> >>>> */
> >>>
> >>> This means that the stack_end address is starting at your very top
> >>> address space (i.e. 16KiB if you set your linker size to 16KiB). The
> stack
> >>> grows dynamically downwards, so it might overflow other sections (e.g.
> work,
> >>> heap, data, etc) if you don't have enough memory size to fit. You can
> try to
> >>> see how much size each section occupies (riscv32-rtems4.12-objdump -h
> >>> hello.exe), especially work space.
> >>>
> >>>
> >>> This is how the SPARC start up stack is done. If you aren't careful,
> this
> >>> may not match the assumption in the default method that carves up the
> >>> workspace.
> >>>
> >>> You need to be careful that the memory regions don't overlap.
> >>>
> >>>
> >>>
> >>>
> >>> > And why there were no space for stack? is it possible to work without
> >>> > stack
> >>> > allocated in
> >>> > linkcmd file?
> >>> > Can RTEMS work with a smaller workspace?
> >>> >
> >>> As far as I remember, 4KiB was the smallest I could allocate for
> >>> workspace to work (with Epiphany). As I suggested before, you might
> want to
> >>> start saving up memory by using the local instruction memory (on
> HiFive) and
> >>> compressed version of RISC-V ISA.
> >>>
> >>>
> >>> Is this a characteristic of this board or the architecture in general?
> I
> >>> had the impression that the RISC-V was quite general purpose and could
> >>> handle plenty of RAM even if some boards don't have much.
> >>>
> >>>
> >> RISC-V itself doesn't put such restrictions on the size of memory (e.g.
> >> Linux, seL4, RTEMS can run on FPGA and/or simulators). There's a
> compressed
> >> extension for RISC-V (like thumb) for platforms that have small memories
> >> same as HiFive. Having such small memory is only HiFive related, not
> RISC-V.
> >>>
> >>>
> >>> > --
> >>> > Regards, Denis Obrezkov
> >>>
> >>>
> >>>
> >>> --
> >>> Hesha
> >>>
> >>> _______________________________________________
> >>> devel mailing list
> >>> devel at rtems.org
> >>> http://lists.rtems.org/mailman/listinfo/devel
> >>>
> >>>
> >>
> >>
> >>
> >> --
> >> Hesham
> >
> > I think that RISC-V Compressed ISA can't reduce .bss and .data sections,
> am
> > I right?
> > So, it seems that space allocated by rtems for its workspace should be
> > reduced.
> >
> Currently all of the sections (including .bss, .text, .data, etc) are
> competing for 16KiB memory, if you reduced the .text (using compressed
> RISC-V and/or ITIM) section size, this gives more space for other
> sections, hence .work and .stack.
>
> >
> > --
> > Regards, Denis Obrezkov
>
>
>
> --
> Hesham
>
In my linkcmd file .text is located in flash:
https://github.com/embeddedden/rtems-riscv/blob/hifive1/c/src/lib/libbsp/riscv32/hifive1/startup/linkcmds
--
Regards, Denis Obrezkov
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