Re: [PATCH v4 1/4] riscv: Remove CONFIG_PHYS_RAM_BASE_FIXED

[Alex Ghiti]

Hi,

Le 13/06/2021 à 02:44, Jisheng Zhang a écrit :
> On Sat, 12 Jun 2021 17:23:51 -0700 (PDT)
> Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote:
>
> > On Sat, 12 Jun 2021 16:23:03 PDT (-0700), emil.renner.berthing@xxxxxxxxx wrote:
> > > On Fri, 4 Jun 2021 at 13:51, Alexandre Ghiti <alex@xxxxxxxx> wrote:
> > > > Make the physical RAM base address available for all kernels, not only
> > > > XIP kernels as it will allow to simplify address conversions macros.
> > >
> > > Am I just reading it wrong or won't this patch make it so that the same kernel
> > > can't run on two chips with physical ram starting at different addresses?
>
> I mentioned this point in http://lists.infradead.org/pipermail/linux-riscv/2021-June/006840.html
>
> > IIUC we were in that position, at least without relocatable kernels.
> > Maybe I'm misunderstanding this, though?
>
> Just my humble opinion, before this series patch, at least geneirc Image
> for RV64 + MMU + !XIP is doable.

This patch declares that the physical ram address is at 0x8000_0000, 
whatever the chip, which may not be the case in practice. I did not 
expect Palmer would take this one and had planned to simply push a v5 
without the first 2 patches, but things happened this week that 
prevented me to do that. IMO, we should just wait for a v5 that I'll 
push when possible (probably today or in the coming days).

Thanks,

Alex

> Thanks
>
> > > /Emil
> > >   
> > > > ---
> > > >   arch/riscv/Kconfig | 6 ------
> > > >   1 file changed, 6 deletions(-)
> > > >
> > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > > index b58596b141fc..3d8e7e4bb45c 100644
> > > > --- a/arch/riscv/Kconfig
> > > > +++ b/arch/riscv/Kconfig
> > > > @@ -493,13 +493,8 @@ config STACKPROTECTOR_PER_TASK
> > > >          def_bool y
> > > >          depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_TLS
> > > >
> > > > -config PHYS_RAM_BASE_FIXED
> > > > -       bool "Explicitly specified physical RAM address"
> > > > -       default n
> > > > -
> > > >   config PHYS_RAM_BASE
> > > >          hex "Platform Physical RAM address"
> > > > -       depends on PHYS_RAM_BASE_FIXED
> > > >          default "0x80000000"
> > > >          help
> > > >            This is the physical address of RAM in the system. It has to be
> > > > @@ -512,7 +507,6 @@ config XIP_KERNEL
> > > >          # This prevents XIP from being enabled by all{yes,mod}config, which
> > > >          # fail to build since XIP doesn't support large kernels.
> > > >          depends on !COMPILE_TEST
> > > > -       select PHYS_RAM_BASE_FIXED
> > > >          help
> > > >            Execute-In-Place allows the kernel to run from non-volatile storage
> > > >            directly addressable by the CPU, such as NOR flash. This saves RAM
> > > > --
> > > > 2.30.2
> > > >
> > > >
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> >
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