linux-kernel - Re: linux-next: Tree for Apr 9 (x86 boot problem)

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Message-ID: <aa83b81e-a03d-b835-6b45-01efc7e08dce@infradead.org>
Date:   Mon, 12 Apr 2021 08:49:49 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        X86 ML <x86@...nel.org>
Subject: Re: linux-next: Tree for Apr 9 (x86 boot problem)

On 4/11/21 11:14 PM, Mike Rapoport wrote:
> Hi Randy,
> 
> On Sun, Apr 11, 2021 at 07:41:37PM -0700, Randy Dunlap wrote:
>> On 4/9/21 4:51 AM, Stephen Rothwell wrote:
>>> Hi all,
>>>
>>> Changes since 20210408:
>>>
>>
>> Hi,
>>
>> I cannot boot linux-next 20210408 nor 20210409 on an antique
>> x86_64 laptop (Toshiba Portege).
>>
>> After many failed tests, I finally resorted to git bisect,
>> which led me to:
>>
>> # bad: [4c674481dcf9974834b96622fa4b079c176f36f9] x86/setup: Merge several reservations of start of memory
>> git bisect bad 4c674481dcf9974834b96622fa4b079c176f36f9
>>
>>
>> I reverted both of these patches and the laptop boots successfully:
>>
>> commit a799c2bd29d19c565f37fa038b31a0a1d44d0e4d
>> Author: Mike Rapoport <rppt@...nel.org>
>> Date:   Tue Mar 2 12:04:05 2021 +0200
>>
>>     x86/setup: Consolidate early memory reservations
>>
>> &&
>>
>> commit 4c674481dcf9974834b96622fa4b079c176f36f9
>> Author: Mike Rapoport <rppt@...nel.org>
>> Date:   Tue Mar 2 12:04:06 2021 +0200
>>
>>     x86/setup: Merge several reservations of start of memory
>>
>>
>> There is no (zero, nil) console display when I try to boot
>> next 0408 or 0409. I connected a USB serial debug cable and
>> booted with earlyprintk=dbgp,keep and still got nothing.
>>
>> The attached boot log is linux-next 20210409 minus the 2 patches
>> listed above.
>>
>> Mike- what data would you like to see?
> 
> Huh, with no console this would be fun :)
> For now the only idea I have is to "bisect" the changes and move
> reservations one by one back to their original place until the system boots
> again. 
> 
> I'd start with trim_snb_memory() since it's surely needed on your laptop
> and quite likely it is a NOP on other systems.
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 776fc9b3fafe..dfca9d6b1aa6 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -746,8 +746,6 @@ static void __init early_reserve_memory(void)
>  
>  	reserve_ibft_region();
>  	reserve_bios_regions();
> -
> -	trim_snb_memory();
>  }
>  
>  /*
> @@ -1081,6 +1079,8 @@ void __init setup_arch(char **cmdline_p)
>  
>  	reserve_real_mode();
>  
> +	trim_snb_memory();
> +
>  	init_mem_mapping();
>  
>  	idt_setup_early_pf();
>  
>> -- 

Hi Mike,
That works fine.
Can you provide another/next step?

If not, I'll try a few things.

thanks.
-- 
~Randy