Re: [Xen-devel] Vmap allocator fails to allocate beyond 128MB

[Vijay Kilari <vijay.kilari@xxxxxxxxx>]

On Mon, Feb 16, 2015 at 3:58 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> On 16/02/15 10:17, Vijay Kilari wrote:
>
> Hello Vijay,
>
>>   For ThunderX/arm64 this issue needs to be fixed.
>> Could you please comment on this?
>
> AFAICS, x86 is also using a 1G area for the vmap. Does it mean that x86
> never use vmap for more than 128M?

I think for x86 there is no problem. It works beyond 128M

>
>> I could think of below
>>
>>         1) Add new call for ARM under CONFIG_ARM_32/CONFIG_ARM_64
>> in vm_init() and manage map_pages_to_xen(va, 0, vm_low - nr, 
>> MAP_SMALL_PAGES);
>> with different function call for arm that would not make any pte
>> entries for vm_bitmap pages.
>> This avoids change to x86
>>
>>         2) Remove map_pages_to_xen(va, 0, vm_low - nr,
>> MAP_SMALL_PAGES) from vm_init
>> and add new architecture specific for initializing vm_bitmap pages.
>> But this touches
>> x86 code.
>
> I don't know which approach is the best, and I though you already talked
> about it with Jan... But in general a generic approach is better than a
> per-architecture solution.

When I say architecture specific, I mean, a common function will be
created and implemented in architecture specific files similar to
map_pages_to_xen. This new function will wrap the required code
for per-architecture.

Vijay

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