From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
the arch/x86 maintainers <x86@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@amacapital.net>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Borislav Petkov <bp@suse.de>, Andi Kleen <ak@linux.intel.com>,
linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv6, RESEND 4/4] x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G
Date: Tue, 23 Jan 2018 20:37:03 +0300 [thread overview]
Message-ID: <20180123173703.rrr7igl7xtlsawhf@node.shutemov.name> (raw)
In-Reply-To: <CA+55aFxgsZCqJdhZJ3ztyTTFPPgkn_aH6d4ziW1g0YJKc++0+A@mail.gmail.com>
On Tue, Jan 23, 2018 at 09:31:16AM -0800, Linus Torvalds wrote:
> On Tue, Jan 23, 2018 at 9:09 AM, Kirill A. Shutemov
> <kirill.shutemov@linux.intel.com> wrote:
> >
> > But if the bootloader put the kernel above 4G (not sure if anybody does
> > this), we would lose control as soon as paging is disabled, because the
> > code becomes unreachable to the CPU.
>
> I do wonder if we need this. Why would a bootloader ever put the data
> above 4G? Does this really happen? Wouldn't it be easier to just say
> "bootloaders better put the kernel in the low 4G"?
I don't know much about bootloaders, but do we even have such guarantee
for in-kernel bootloader -- kexec?
--
Kirill A. Shutemov
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next prev parent reply other threads:[~2018-01-23 17:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 17:09 [PATCHv6, RESEND 0/4] x86: 5-level related changes into decompression code Kirill A. Shutemov
2018-01-23 17:09 ` [PATCHv6, RESEND 1/4] x86/boot/compressed/64: Rename pagetable.c to kaslr_64.c Kirill A. Shutemov
2018-01-23 17:09 ` [PATCHv6, RESEND 2/4] x86/boot/compressed/64: Introduce paging_prepare() Kirill A. Shutemov
2018-01-23 17:09 ` [PATCHv6, RESEND 3/4] x86/boot/compressed/64: Prepare trampoline memory Kirill A. Shutemov
2018-01-23 17:09 ` [PATCHv6, RESEND 4/4] x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G Kirill A. Shutemov
2018-01-23 17:31 ` Linus Torvalds
2018-01-23 17:37 ` Kirill A. Shutemov [this message]
2018-01-23 18:13 ` Andi Kleen
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