[PATCH v2] lib: sbi: Add option to select boot hart

[Cheehong Ang]

> -----Original Message-----
> From: Anup Patel <apatel at ventanamicro.com>
> Sent: Friday, December 2, 2022 7:36 PM
> To: WeiLiang Lim <weiliang.lim at starfivetech.com>
> Cc: opensbi at lists.infradead.org; Cheehong Ang
> <cheehong.ang at starfivetech.com>; JunLiang Tan
> <junliang.tan at starfivetech.com>
> Subject: Re: [PATCH v2] lib: sbi: Add option to select boot hart
> 
> On Fri, Dec 2, 2022 at 1:21 PM Anup Patel <apatel at ventanamicro.com> wrote:
> >
> > On Fri, Dec 2, 2022 at 12:10 PM Wei Liang Lim
> > <weiliang.lim at starfivetech.com> wrote:
> > >
> > > In certain scenario, user needs to select a particular hart ID as the boot hart.
> This option provide the flexibility for user to select the preferred boot hart.
> > >
> > > Signed-off-by: Wei Liang Lim <weiliang.lim at starfivetech.com>
> > > Reviewed-by: Chee Hong Ang <cheehong.ang at starfivetech.com>
> > > Reviewed-by: Jun Liang Tan <junliang.tan at starfivetech.com>
> > > ---
> > >  firmware/objects.mk | 4 ++++
> > >  lib/sbi/sbi_init.c  | 6 ++++++
> > >  2 files changed, 10 insertions(+)
> > >
> > > diff --git a/firmware/objects.mk b/firmware/objects.mk index
> > > a1704c4..2b41718 100644
> > > --- a/firmware/objects.mk
> > > +++ b/firmware/objects.mk
> > > @@ -28,6 +28,10 @@ ifdef FW_TEXT_START  firmware-genflags-y +=
> > > -DFW_TEXT_START=$(FW_TEXT_START)  endif
> > >
> > > +ifdef FW_BOOT_HART_ID
> > > +firmware-genflags-y += -DFW_BOOT_HART_ID=$(FW_BOOT_HART_ID)
> > > +endif
> > > +
> > >  ifdef FW_FDT_PATH
> > >  firmware-genflags-y += -DFW_FDT_PATH=\"$(FW_FDT_PATH)\"
> > >  ifdef FW_FDT_PADDING
> > > diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c index
> > > a8500e5..28698f1 100644
> > > --- a/lib/sbi/sbi_init.c
> > > +++ b/lib/sbi/sbi_init.c
> > > @@ -447,7 +447,9 @@ static void __noreturn init_warmboot(struct
> sbi_scratch *scratch, u32 hartid)
> > >                              scratch->next_mode, FALSE);  }
> > >
> > > +#ifndef FW_BOOT_HART_ID
> > >  static atomic_t coldboot_lottery = ATOMIC_INITIALIZER(0);
> > > +#endif
> > >
> > >  /**
> > >   * Initialize OpenSBI library for current HART and jump to next @@
> > > -498,7 +500,11 @@ void __noreturn sbi_init(struct sbi_scratch *scratch)
> > >          * HARTs which satisfy above condition.
> > >          */
> > >
> > > +#ifdef FW_BOOT_HART_ID
> > > +       if (next_mode_supported && hartid == FW_BOOT_HART_ID) #else
> >
> > This breaks the CPU hotplug for boot HART.
> >
> > In other words, the boot HART will now always take coldboot path when
> > it is stopped (sbi_hsm_hart_stop()) and started (sbi_hsm_hart_start())
> > at runtime.
> 
> Can you try the two experimental patches from preferred_cold_boot_hart_v1
> branch at: https://github.com/avpatel/opensbi.git ?
> 
> You will need to implement your platform specific override on top of these
> patches to decide which HARTs are allowed to do cold boot. If it works for you
> then include these patches in your v3 patches.
> 
> Regards,
> Anup
Great! Thanks! This is exactly what we are looking for. This is so much better as we can
override the preferred cold boot hart behaviour in platform specific code.
We will integrate these 2 patches and test with our platform code.
BTW, our platform specific code is not quite ready to be upstreamed with these 2 patches for now yet.
Can we get back to you with the test result and you can just merge these 2 patches into mainline ?
Or you expect us to include these 2 patches as well when we upstream our platform code later ?
> 
> >
> > >         if (next_mode_supported && atomic_xchg(&coldboot_lottery, 1)
> > > == 0)
> > > +#endif
> > >                 coldboot = TRUE;
> > >
> > >         /*
> > > --
> > > 2.25.1
> > >
> > >
> > > --
> > > opensbi mailing list
> > > opensbi at lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/opensbi
> >
> > Regards,
> > Anup