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

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Date:   Tue, 13 Apr 2021 10:34:25 -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 4/13/21 9:58 AM, Mike Rapoport wrote:
> On Mon, Apr 12, 2021 at 11:21:48PM -0700, Randy Dunlap wrote:
>> On 4/12/21 11:06 PM, Mike Rapoport wrote:
>>> Hi Randy,
>>>
>>> On Mon, Apr 12, 2021 at 01:53:34PM -0700, Randy Dunlap wrote:
>>>> On 4/12/21 10:01 AM, Mike Rapoport wrote:
>>>>> On Mon, Apr 12, 2021 at 08:49:49AM -0700, Randy Dunlap wrote:
>>>>>  
>>>>> I thought about adding some prints to see what's causing the hang, the
>>>>> reservations or their absence. Can you replace the debug patch with this
>>>>> one:
>>>>>
>>>>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>>>>> index 776fc9b3fafe..a10ac252dbcc 100644
>>>>> --- a/arch/x86/kernel/setup.c
>>>>> +++ b/arch/x86/kernel/setup.c
>>>>> @@ -600,10 +600,13 @@ static bool __init snb_gfx_workaround_needed(void)
>>>>>  		return false;
>>>>>  
>>>>>  	vendor = read_pci_config_16(0, 2, 0, PCI_VENDOR_ID);
>>>>> +	devid = read_pci_config_16(0, 2, 0, PCI_DEVICE_ID);
>>>>> +
>>>>> +	pr_info("%s: vendor: %x, device: %x\n", __func__, vendor, device);
>>>>
>>>> s/device)/devid)/
>>>  
>>> Oh, sorry.
>>>
>>>>> +
>>>>>  	if (vendor != 0x8086)
>>>>>  		return false;
>>>>>  
>>>>> -	devid = read_pci_config_16(0, 2, 0, PCI_DEVICE_ID);
>>>>>  	for (i = 0; i < ARRAY_SIZE(snb_ids); i++)
>>>>>  		if (devid == snb_ids[i])
>>>>>  			return true;
>>>>
>>>> That prints:
>>>>
>>>> [    0.000000] snb_gfx_workaround_needed: vendor: 8086, device: 126
>>>> [    0.000000] early_reserve_memory: snb_gfx: 1
>>>> ...
>>>> [    0.014061] snb_gfx_workaround_needed: vendor: 8086, device: 126
>>>> [    0.014064] reserving inaccessible SNB gfx pages
>>>>
>>>>
>>>> The full boot log is attached.
>>>  
>>> Can you please send the log with memblock=debug added to the kernel command
>>> line?
>>>
>>> Probably should have started from this...
>>>
>>
>> It's attached.
> 
> Honestly, I can't see any reason why moving these reservations around would
> cause your laptop to hang.
> Let's try moving the reservations back to their original place one by
> one, e.g something like this:
> 
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 776fc9b3fafe..892ad20b8557 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -632,12 +632,6 @@ static void __init trim_snb_memory(void)
>  
>  	printk(KERN_DEBUG "reserving inaccessible SNB gfx pages\n");
>  
> -	/*
> -	 * Reserve all memory below the 1 MB mark that has not
> -	 * already been reserved.
> -	 */
> -	memblock_reserve(0, 1<<20);
> -	
>  	for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
>  		if (memblock_reserve(bad_pages[i], PAGE_SIZE))
>  			printk(KERN_WARNING "failed to reserve 0x%08lx\n",
> @@ -1081,6 +1075,12 @@ void __init setup_arch(char **cmdline_p)
>  
>  	reserve_real_mode();
>  
> +	/*
> +	 * Reserve all memory below the 1 MB mark that has not
> +	 * already been reserved.
> +	 */
> +	memblock_reserve(0, 1<<20);
> +
>  	init_mem_mapping();
>  
>  	idt_setup_early_pf();
> 

Mike,
That works.

Please send the next test.

-- 
~Randy