linux-kernel - Re: [PATCH v5 09/10] ARM: sunplus: Add initial support for Sunplus SP7021 SoC

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Message-ID: <CAK8P3a2w2rava_ozRfWizYDYRe7J3j-=wMgzGA_9t0kd3qJ1NA@mail.gmail.com>
Date:   Thu, 9 Dec 2021 10:58:05 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     qinjian[覃健] <qinjian@...lus1.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Mark Brown <broonie@...nel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Wells Lu 呂芳騰 <wells.lu@...plus.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Linus Walleij <linusw@...nel.org>
Subject: Re: [PATCH v5 09/10] ARM: sunplus: Add initial support for Sunplus
 SP7021 SoC

On Thu, Dec 9, 2021 at 9:49 AM qinjian[覃健] <qinjian@...lus1.com> wrote:
> > On Tue, Dec 7, 2021 at 8:21 AM qinjian[覃健] <qinjian@...lus1.com> wrote:
> > > > > @@ -152,6 +152,7 @@ textofs-$(CONFIG_ARCH_MSM8X60) := 0x00208000
> > > > >  textofs-$(CONFIG_ARCH_MSM8960) := 0x00208000
> > > > >  textofs-$(CONFIG_ARCH_MESON) := 0x00208000
> > > > >  textofs-$(CONFIG_ARCH_AXXIA) := 0x00308000
> > > > > +textofs-$(CONFIG_ARCH_SUNPLUS) := 0x00308000
> > > >
> > > > What is this needed for? If it boots without this line, better avoid
> > > > adding it, because
> > > > it will increase the kernel size for everyone else (unless they also enable
> > > > AXXIA).
> > > >
> > >
> > > SP7021 reserved the 1st 1MB memory for ARM926@...hip using,
> > > The 2nd 1MB memory for IOP device and the 3rd 1MB memory for bootloader.
> > > I'll add these comments at next commit.
> >
> > I think you can just remove the memory from the system memory map in the
> > device tree and pretend it only starts after the bootloader. It's been a while
> > since I looked at this though, so I could be misremembering what the minimum
> > boundaries are for doing this.
>
> I have test following 3 methods:

Right, I was thinking of the third method here, which has the advantage of
not requiring the same odd base address for all other platforms, this
is important to us.
I don't see what the problem is with it in your example, does that mean you
have a little less usable memory, or that something fails to work right? I don't
know what the requirements are for memreserve.

Adding a few more people to Cc, maybe they have ideas about how this
was solved elsewhere.

          Arnd

> 1. current patch
> DT:
>         memory {
>                 reg = <0x00000000 0x20000000>; /* 512MB */
>         };
>
>         reserved-memory {
>                 #address-cells = <1>;
>                 #size-cells = <1>;
>                 ranges;
>
>                 iop_reserve: iop_device {
>                         no-map;
>                         reg = <0x00100000 0x00100000>;
>                 };
>                 a926_reserve: a926_memory {
>                         no-map;
>                         reg = <0x00000000 0x00100000>;
>                 };
>         };
> arch/arm/Makefile:
>         textofs-$(CONFIG_ARCH_SUNPLUS) := 0x00308000
>
> bootlog & meminfo :
> [    0.000000] Zone ranges:
> [    0.000000]   Normal   [mem 0x0000000000000000-0x000000001fffffff]
> [    0.000000] Movable zone start for each node
> [    0.000000] Early memory node ranges
> [    0.000000]   node   0: [mem 0x0000000000000000-0x00000000001fffff]
> [    0.000000]   node   0: [mem 0x0000000000200000-0x000000001fffffff]
> [    0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x000000001fffffff]
>
> ~ # cat /proc/meminfo
> MemTotal:         514008 kB
> MemFree:          491960 kB
> MemAvailable:     488608 kB
>
>
>
> 2. DT same as case 1, but no modify @ arch/arm/Makefile
>
> bootlog & meminfo :
> [    0.000000] OF: fdt: Reserved memory: failed to reserve memory for node 'iop_device': base 0x00100000, size 1 MiB
> [    0.000000] OF: fdt: Reserved memory: failed to reserve memory for node 'a926_memory': base 0x00000000, size 1 MiB
> ...
> [    0.000000] Zone ranges:
> [    0.000000]   Normal   [mem 0x0000000000000000-0x000000001fffffff]
> [    0.000000] Movable zone start for each node
> [    0.000000] Early memory node ranges
> [    0.000000]   node   0: [mem 0x0000000000000000-0x000000001fffffff]
> [    0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x000000001fffffff]
>
> ~ # cat /proc/meminfo
> MemTotal:         516056 kB
> MemFree:          493928 kB
> MemAvailable:     490572 kB
>
>
>
> 3. DT:
>         memory {
>                 reg = <0x00300000 0x1FD00000>; /* 512 - 3 MB */
>         };
> no modify @ arch/arm/Makefile
>
> bootlog & meminfo :
> [    0.000000] Zone ranges:
> [    0.000000]   Normal   [mem 0x0000000000400000-0x000000001fffffff]
> [    0.000000] Movable zone start for each node
> [    0.000000] Early memory node ranges
> [    0.000000]   node   0: [mem 0x0000000000400000-0x000000001fffffff]
> [    0.000000] Initmem setup node 0 [mem 0x0000000000400000-0x000000001fffffff]
>
> ~ # cat /proc/meminfo
> MemTotal:         511964 kB
> MemFree:          489636 kB
> MemAvailable:     486292 kB
>
>
>
> I think method 1 should be correct (compare method 2) & better (compare method 3).
>