Re: l1tf: Kernel suggests I throw away third of my memory. I'd rather not

[Vlastimil Babka]

On 10/17/18 4:08 PM, Andi Kleen wrote:
> On Wed, Oct 17, 2018 at 12:56:10PM +0200, Pavel Machek wrote:
>> Hi!
>>
>> 6a012288 suggests I throw away 1GB on RAM. On 3GB system.. that is not
>> going to be pleasant.
> 
> Just rebuild your kernel with PAE? I assume your CPU supports it.

I think it is built with PAE or this would kick in:

#if CONFIG_PGTABLE_LEVELS == 2
        pr_warn("Kernel not compiled for PAE. No mitigation for L1TF\n");
        return;
#endif

I.e. no MAX_PA/2 messages.

> This will also give you NX, which if you're really worried
> about security is far more important than L1TF.
> 
> If you don't worry about security just ignore.
> 
> -Andi
>