On Thu, Mar 22, 2012 at 08:41:35AM +0800, Wang YanQing wrote:

On Wed, Mar 14, 2012 at 11:21:37AM +0000, Alan Cox wrote:

quoted

You can use set_memory_x() to mark memory executable (and _nx to set it back).

NO I can't, if I set_memory_x and don't set pcibios_enabled = 1, then
static_protections will still failed because pcibios_enabled == 0, 
and I don't want to use set_memory_x, because I don't want to give the user 
of uvesafb that feeling "I will lost BIOS NX protection if I choice uvesafb."

quoted

If you really need to know if NX is being used then the check

	if (__supported_pte_mask & PTE_NX)

will do the trick and the variable is exported.

I don't understand what do you mean, do you means CONFIG_X86_PAE for 32? Or CONFIG_X86_64?
when NX is being used, the pci bios is NX or not also depend on
ACPI.ACPI on or off all will influnce the code path in pci_arch_init,
decide the set_bios_x have chance to execute or not.See
https://lkml.org/lkml/2011/11/16/84

By the way _PAGE_NX instead of PTE_NX, right?

quoted

I'd suggest however you wrap that in a cpu_has_nx() type macro somewhere
in the arch headers.

The same above.

quoted

If you go poking around pcibios values you are going to get burned if
someone is ever bored enough to make NX and PCIBIOS work together
differently.

Indeed according to 5bd5a452662bc37c54fb6828db1a3faf87e6511c, who bring me 
the trouble, check the pcibios_enabled is the only simple and good way to 
resolve the Oops I meet.

If you really don't want it, and if I am not all wrong about your "helper method",
you means you want export the below:
int check_pcibios_enabled()?
See https://lkml.org/lkml/2012/2/26/124

Thanks.

Sorry for the delay reply and cross email threads,  Alan Cox.
But I still can't find a better way then to check the pcibios_enabled variable,
any better suggestion?