Re: [PATCH 02/12] RISC-V: MAXPHYSMEM_2GB doesn't depend on CMODEL_MEDLOW

[Alexandre ghiti]

Hi Conor,

On 1/14/22 09:40, Conor.Dooley@xxxxxxxxxxxxx wrote:
> On 11/01/2022 16:04, Geert Uytterhoeven wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >
> > Hi Palmer,
> >
> > On Fri, Nov 19, 2021 at 5:47 PM Palmer Dabbelt <palmer@xxxxxxxxxxxx> wrote:
> > > From: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
> > >
> > > For non-relocatable kernels we need to be able to link the kernel at
> > > approximately PAGE_OFFSET, thus requiring medany (as medlow requires the
> > > code to be linked within 2GiB of 0).  The inverse doesn't apply, though:
> > > since medany code can be linked anywhere it's fine to link it close to
> > > 0, so we can support the smaller memory config.
> > >
> > > Fixes: de5f4b8f634b ("RISC-V: Define MAXPHYSMEM_1GB only for RV32")
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
> > Thanks for your patch, which is now commit 9f36b96bc70f9707 ("RISC-V:
> > MAXPHYSMEM_2GB doesn't depend on CMODEL_MEDLOW").
> >
> > > I found this when going through the savedefconfig diffs for the K210
> > > defconfigs.  I'm not entirely sure they're doing the right thing here
> > > (they should probably be setting CMODEL_LOW to take advantage of the
> > > better code generation), but I don't have any way to test those
> > > platforms so I don't want to change too much.
> > I can confirm MAXPHYSMEM_2GB works on K210 with CMODEL_MEDANY.
> >
> > As the Icicle has 1760 MiB of RAM, I gave it a try with MAXPHYSMEM_2GB
> > (and CMODEL_MEDANY), too.  Unfortunately it crashes very early
> > (needs earlycon to see):
> Given you said 1760 MiB I assume you're not running the device tree
> currently in the kernel?
> But the defconfig is /arch/riscv/configs/defconfig?
>
> I tested it w/ my newer version of the dts, using both 1760 & 736 MiB
> (ddrc_cache_lo only) w/ MAXPHYSMEM_2GB.
> Enabling MAXPHYSMEM_2GB with either CMODEL_MEDANY or CMODEL_MEDLOW
> lead to the same boot failure as you got.


Any chance you can give a try to [1] so that I can extract it from my 
sv48 patchset and propose it to fixes if it works?

Thanks,

Alex

https://patchwork.kernel.org/project/linux-riscv/patch/20211206104657.433304-6-alexandre.ghiti@xxxxxxxxxxxxx/


> >       OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
> >       Machine model: Microchip PolarFire-SoC Icicle Kit
> >       printk: debug: ignoring loglevel setting.
> >       earlycon: ns16550a0 at MMIO32 0x0000000020100000 (options '115200n8')
> >       printk: bootconsole [ns16550a0] enabled
> >       printk: debug: skip boot console de-registration.
> >       efi: UEFI not found.
> >       Unable to handle kernel paging request at virtual address ffffffff87e00001
> >       Oops [#1]
> >       Modules linked in:
> >       CPU: 0 PID: 0 Comm: swapper Not tainted 5.16.0-08771-g85515233477d #56
> >       Hardware name: Microchip PolarFire-SoC Icicle Kit (DT)
> >       epc : fdt_check_header+0x14/0x208
> >        ra : early_init_dt_verify+0x16/0x94
> >       epc : ffffffff802ddacc ra : ffffffff8082415a sp : ffffffff81203ee0
> >        gp : ffffffff812ec3a8 tp : ffffffff8120cd80 t0 : 0000000000000005
> >        t1 : 0000001040000000 t2 : ffffffff80000000 s0 : ffffffff81203f00
> >        s1 : ffffffff87e00000 a0 : ffffffff87e00000 a1 : 000000040ffffce7
> >        a2 : 00000000000000e7 a3 : ffffffff8080394c a4 : 0000000000000000
> >        a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000000000000
> >        s2 : ffffffff81203f98 s3 : 8000000a00006800 s4 : fffffffffffffff3
> >        s5 : 0000000000000000 s6 : 0000000000000001 s7 : 0000000000000000
> >        s8 : 0000000020236c20 s9 : 0000000000000000 s10: 0000000000000000
> >        s11: 0000000000000000 t3 : 0000000000000018 t4 : 00ff000000000000
> >        t5 : 0000000000000000 t6 : 0000000000000010
> >       status: 0000000200000100 badaddr: ffffffff87e00001 cause: 000000000000000d
> >       [<ffffffff802ddacc>] fdt_check_header+0x14/0x208
> >       [<ffffffff8082415a>] early_init_dt_verify+0x16/0x94
> >       [<ffffffff80802dee>] setup_arch+0xec/0x4ec
> >       [<ffffffff80800700>] start_kernel+0x88/0x6d6
> >       random: get_random_bytes called from
> > print_oops_end_marker+0x22/0x44 with crng_init=0
> >       ---[ end trace 903df1a0ade0b876 ]---
> >       Kernel panic - not syncing: Attempted to kill the idle task!
> >       ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---
> >
> > So the FDT is at 0xffffffff87e00000, i.e. at 0x7e00000 from the start
> > of virtual memory (CONFIG_PAGE_OFFSET=0xffffffff80000000), and thus
> > within the 2 GiB range.
> >
> > > --- a/arch/riscv/Kconfig
> > > +++ b/arch/riscv/Kconfig
> > > @@ -280,7 +280,7 @@ choice
> > >                   depends on 32BIT
> > >                   bool "1GiB"
> > >           config MAXPHYSMEM_2GB
> > > -               depends on 64BIT && CMODEL_MEDLOW
> > > +               depends on 64BIT
> > >                   bool "2GiB"
> > >           config MAXPHYSMEM_128GB
> > >                   depends on 64BIT && CMODEL_MEDANY
> > Gr{oetje,eeting}s,
> >
> >                           Geert
> >
> > --
> > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
> >
> > In personal conversations with technical people, I call myself a hacker. But
> > when I'm talking to journalists I just say "programmer" or something like that.
> >                                   -- Linus Torvalds
> >
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