Re: [PATCHv7 12/19] x86/mm: Adjust virtual address space layout in early boot.

From	Ingo Molnar <mingo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCHv7 12/19] x86/mm: Adjust virtual address space layout in early boot.
Date	2017-09-28 10:40 +0200
Message-ID	<uuCwr-6Fg-33@gated-at.bofh.it> (permalink)
References	<ur1Wp-5gk-5@gated-at.bofh.it> <ur265-5yD-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

* Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote:

> We need to adjust virtual address space to support switching between
> paging modes.
> 
> The adjustment happens in __startup_64().

> +#ifdef CONFIG_X86_5LEVEL
> +	if (__read_cr4() & X86_CR4_LA57) {
> +		pgtable_l5_enabled = 1;
> +		pgdir_shift = 48;
> +		ptrs_per_p4d = 512;
> +	}
> +#endif

So CR4 really sucks as a parameter passing interface - was it us who enabled LA57 
in the early boot code, right? Couldn't we add a flag which gets set there, or 
something?

Thanks,

	Ingo

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: [PATCHv7 12/19] x86/mm: Adjust virtual address space layout in  early boot. Ingo Molnar <mingo@kernel.org> - 2017-09-28 10:40 +0200
  Re: [PATCHv7 12/19] x86/mm: Adjust virtual address space layout in  early boot. "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-09-28 15:30 +0200
    Re: [PATCHv7 12/19] x86/mm: Adjust virtual address space layout in  early boot. Ingo Molnar <mingo@kernel.org> - 2017-09-28 15:40 +0200
      Re: [PATCHv7 12/19] x86/mm: Adjust virtual address space layout in  early boot. "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-09-28 16:30 +0200

csiph-web