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

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Date:   Fri, 14 Jan 2022 10:09:03 +0100
From:   Alexandre ghiti <alex@...ti.fr>
To:     Conor.Dooley@...rochip.com, geert@...ux-m68k.org,
        palmer@...osinc.com
Cc:     linux-riscv@...ts.infradead.org, paul.walmsley@...ive.com,
        palmer@...belt.com, aou@...s.berkeley.edu,
        heinrich.schuchardt@...onical.com, bin.meng@...driver.com,
        sagar.kadam@...ive.com, damien.lemoal@....com, axboe@...nel.dk,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 02/12] RISC-V: MAXPHYSMEM_2GB doesn't depend on
 CMODEL_MEDLOW

Hi Conor,

On 1/14/22 09:40, Conor.Dooley@...rochip.com 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@...osinc.com> wrote:
>>> From: Palmer Dabbelt <palmer@...osinc.com>
>>>
>>> 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@...r.kernel.org
>>> Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
>> 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@canonical.com/

>>       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@...ux-m68k.org
>>
>> 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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