Re: [RFC] A simple way to determine if the kernel needs HIGHMEM64Gto be able to use all the installed memory

[Alexey Dobriyan]

On Sat, Mar 07, 2009 at 01:04:38PM +0200, Ozan ÃaÄlayan wrote:
> When the installed memory size is >= 4GB, kernel drops some messages like
> 
> Warning only 4GB of memory will be used
> You have to enable HIGHMEM64G.
> 
> I checked that the message comes from arch/x86/init_32.c after checking
> max_pfn.
> 
> I'm quite dumb about the internal structures of the kernel but, wouldn't it
> be possible to create a simple read-only sysfs object like kexec_loaded
> that will contain "1" when the kernel needs HIGHMEM64G to see all of the memory
> and "0" when it doesn't?

Why do you need a file? If kernel says to enable HIGHMEM64G, enable it.

> I think that it would be a nice facility for distribution kernels to detect
> the need for a PAE enabled 32-bit kernel by just reading some /sys/.. entry.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/