Re: [CFT] ELF Relocatable x86 and x86_64 bzImages

[ebiederm@xmission.com (Eric W. Biederman)]

Andi Kleen <ak@suse.de> writes:

> ebiederm@xmission.com (Eric W. Biederman) writes:
>> 
>> Do you know what code had problems having _PAGE_NX set.
>> What are we doing with early_ioremap the requires execute
>> permissions.  It doesn't sound right that we would need
>> this.
>
> The early EM64T CPUs didn't support NX and would GPF when
> they hit the bit. That is why you always need to mask 
> with __supported_pte_mask when using _PAGE_NX.

Ok.  Thanks.  That explains that it.

The NX bit itself causes the GPF not someone trying to execute
data on a page.

Eric
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