linux-kernel - Re: [Xen-devel] [PATCH V2 2/3] xen: eliminate scalability issues from initrd handling

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Date:	Wed, 17 Sep 2014 16:01:33 +0200
From:	Juergen Gross <jgross@...e.com>
To:	David Vrabel <david.vrabel@...rix.com>,
	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
	konrad.wilk@...cle.com, boris.ostrovsky@...cle.com,
	jbeulich@...e.com
Subject: Re: [Xen-devel] [PATCH V2 2/3] xen: eliminate scalability issues
 from initrd handling

On 09/17/2014 03:45 PM, David Vrabel wrote:
> On 17/09/14 05:12, Juergen Gross wrote:
>> Size restrictions native kernels wouldn't have resulted from the initrd
>> getting mapped into the initial mapping. The kernel doesn't really need
>> the initrd to be mapped, so use infrastructure available in Xen to avoid
>> the mapping and hence the restriction.
>>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
>> ---
>>   arch/x86/xen/enlighten.c | 11 +++++++++--
>>   arch/x86/xen/xen-head.S  |  1 +
>>   2 files changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
>> index c0cb11f..8fd075f 100644
>> --- a/arch/x86/xen/enlighten.c
>> +++ b/arch/x86/xen/enlighten.c
>> @@ -1519,6 +1519,7 @@ static void __init xen_pvh_early_guest_init(void)
>>   asmlinkage __visible void __init xen_start_kernel(void)
>>   {
>>   	struct physdev_set_iopl set_iopl;
>> +	unsigned long initrd_start = 0;
>>   	int rc;
>>
>>   	if (!xen_start_info)
>> @@ -1667,10 +1668,16 @@ asmlinkage __visible void __init xen_start_kernel(void)
>>   	new_cpu_data.x86_capability[0] = cpuid_edx(1);
>>   #endif
>>
>> +	if (xen_start_info->mod_start)
>> +		initrd_start = __pa(xen_start_info->mod_start);
>> +#ifdef CONFIG_BLK_DEV_INITRD
>> +	if (xen_start_info->flags & SIF_MOD_START_PFN)
>> +		initrd_start = PFN_PHYS(xen_start_info->mod_start);
>> +#endif
>
> Why the #ifdef?
>
> I'll fix this up to be:
>
>     if (xen_start_info->mod_start) {
>         if (xen_start_info->flags & SIF_MOD_START_PFN)
>             initrd_start = PFN_PHYS_(xen_start_info->mod_start);
>         else
>             initrd_start = __pa(xen_start_info->mod_start);
>     }
>
> Unless you object.

Yeah, you are right. This seems to be okay.


Juergen

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