On Fri, 7 May 2021 16:44:24 +0200
Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> wrote:
Hi Ahmad !
> Hello Antony,
>
> On 07.05.21 16:25, Antony Pavlov wrote:
> >> I would really like to have a riscv{32,64}_defconfig that can just build all boards
> >> at once. Do you know if this could be dynamically determined?
> >
> > At the moment I have not answer.
> > I'll try to investigate dynamic mode determination, it's very attractive idea.
> >
> > On the other hand compile time mode selection is not the show stopper for
> > "one defconfig to build them all": we have to make STACK_SIZE and MALLOC_SIZE
> > per-board parameters not per-defconfig parameters like now.
> >
> > If we could make STACK_SIZE and MALLOC_SIZE per-board compile-time parameters then
> > we can make RISC-V mode per-board compile-time parameter too. Is this solution
> > acceptable?
>
> MALLOC_SIZE can be set as 0 and barebox will determine it based on
> membase + memsize that are set by PBL.
>
> STACK_SIZE must be set per Kconfig, but I think even a generous default stack
> size should accommodate all targets.
>
> If we do the same for RISC-V mode that would probably mean having
> two functions barebox_riscv_machine_entry() and barebox_riscv_supervisor_entry()
> in PBL that take care to pass the correct info to barebox proper.
>
> Apparently, you can determine mode if you catch exceptions:
> https://forums.sifive.com/t/how-to-determine-the-current-execution-privilege-mode/2823
Hmm, answer is mostly negative:
<<
RISC-V deliberately doesn’t make it easy for code to discover
what mode it is running it because this is a virtualisation hole.
As a general principle, code should be designed for and implicitly
know what mode it will run in.
>>
> We don't yet install exception handlers in barebox, but I am fine with using
> different PBL common code entry functions.
>
> What do you think?
I think that adding exception handling to barebox would be very handy.
At the moment barebox sometimes hangs during my experiments without any error message.
Even with a simple exception handler that just prints out epc, status and cause registers
I have much more information on hang reason.
--
Best regards,
Antony Pavlov
> >
> >>> +
> >>> source "arch/riscv/Kconfig.socs"
> >>>
> >>> config CPU_SUPPORTS_32BIT_KERNEL
> >>> @@ -97,14 +109,4 @@ config NMON_HELP
> >>> Say yes here to get the nmon commands message on
> >>> every nmon start.
> >>>
> >>> -# set if we run in machine mode, cleared if we run in supervisor mode
> >>> -config RISCV_M_MODE
> >>> - bool
> >>> -
> >>> -# set if we are running in S-mode and can use SBI calls
> >>> -config RISCV_SBI
> >>> - bool
> >>> - depends on !RISCV_M_MODE
> >>> - default y
> >>> -
> >>> endmenu
> >>> diff --git a/arch/riscv/Kconfig.socs b/arch/riscv/Kconfig.socs
> >>> index c6875738d0..f767942f34 100644
> >>> --- a/arch/riscv/Kconfig.socs
> >>> +++ b/arch/riscv/Kconfig.socs
> >>> @@ -3,10 +3,10 @@ menu "SoC selection"
> >>> config SOC_ERIZO
> >>> bool "Erizo SoC"
> >>> depends on ARCH_RV32I
> >>> + depends on RISCV_M_MODE
> >>> select HAS_ASM_DEBUG_LL
> >>> select HAS_NMON
> >>> select USE_COMPRESSED_DTB
> >>> - select RISCV_M_MODE
> >>> select RISCV_TIMER
> >>>
> >>> config BOARD_ERIZO_GENERIC
> >>> @@ -15,6 +15,7 @@ config BOARD_ERIZO_GENERIC
> >>>
> >>> config SOC_VIRT
> >>> bool "QEMU Virt Machine"
> >>> + depends on RISCV_SBI
> >>> select BOARD_RISCV_GENERIC_DT
> >>> select CLINT_TIMER
> >>> help
> >>> @@ -23,6 +24,7 @@ config SOC_VIRT
> >>>
> >>> config SOC_SIFIVE
> >>> bool "SiFive SoCs"
> >>> + depends on RISCV_SBI
> >>> select CLK_SIFIVE
> >>> select CLK_SIFIVE_PRCI
> >>> select RISCV_TIMER
> >>> diff --git a/arch/riscv/configs/erizo_generic_defconfig b/arch/riscv/configs/erizo_generic_defconfig
> >>> index 247a179130..16168eef66 100644
> >>> --- a/arch/riscv/configs/erizo_generic_defconfig
> >>> +++ b/arch/riscv/configs/erizo_generic_defconfig
> >>> @@ -1,3 +1,4 @@
> >>> +CONFIG_RISCV_M_MODE=y
> >>> CONFIG_SOC_ERIZO=y
> >>> # CONFIG_GLOBALVAR is not set
> >>> CONFIG_STACK_SIZE=0x20000
> >>>
> >>
> >> --
> >> Pengutronix e.K. | |
> >> Steuerwalder Str. 21 | http://www.pengutronix.de/ |
> >> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
> >> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
> >
> >
>
> --
> Pengutronix e.K. | |
> Steuerwalder Str. 21 | http://www.pengutronix.de/ |
> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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