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From: Ingo Molnar <mingo@kernel.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Andi Kleen <ak@linux.intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Andy Lutomirski <luto@amacapital.net>,
	linux-arch@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/8] x86/boot/64: Add support of additional page table level during early boot
Date: Tue, 11 Apr 2017 13:28:45 +0200	[thread overview]
Message-ID: <20170411112845.GA15212@gmail.com> (raw)
In-Reply-To: <20170411105106.4zgbzuu4s4267zyv@node.shutemov.name>


* Kirill A. Shutemov <kirill@shutemov.name> wrote:

> On Tue, Apr 11, 2017 at 09:02:03AM +0200, Ingo Molnar wrote:
> > I realize that you had difficulties converting this to C, but it's not going to 
> > get any easier in the future either, with one more paging mode/level added!
> > 
> > If you are stuck on where it breaks I'd suggest doing it gradually: first add a 
> > trivial .c, build and link it in and call it separately. Then once that works, 
> > move functionality from asm to C step by step and test it at every step.
> 
> I've described the specific issue with converting this code to C in cover
> letter: how to make compiler to generate 32-bit code for a specific
> function or translation unit, without breaking linking afterwards (-m32
> break it).

Have you tried putting it into a separate .c file, and building it 32-bit?

I think arch/x86/entry/vdso/Makefile contains an example of how to build 32-bit 
code even on 64-bit kernels.

Thanks,

	Ingo

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WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Andi Kleen <ak@linux.intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Andy Lutomirski <luto@amacapital.net>,
	linux-arch@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/8] x86/boot/64: Add support of additional page table level during early boot
Date: Tue, 11 Apr 2017 13:28:45 +0200	[thread overview]
Message-ID: <20170411112845.GA15212@gmail.com> (raw)
Message-ID: <20170411112845.Q2Hb4HNNik0Fm8rz9nUx6Zord8w3nW90b1COVxJC_qI@z> (raw)
In-Reply-To: <20170411105106.4zgbzuu4s4267zyv@node.shutemov.name>


* Kirill A. Shutemov <kirill@shutemov.name> wrote:

> On Tue, Apr 11, 2017 at 09:02:03AM +0200, Ingo Molnar wrote:
> > I realize that you had difficulties converting this to C, but it's not going to 
> > get any easier in the future either, with one more paging mode/level added!
> > 
> > If you are stuck on where it breaks I'd suggest doing it gradually: first add a 
> > trivial .c, build and link it in and call it separately. Then once that works, 
> > move functionality from asm to C step by step and test it at every step.
> 
> I've described the specific issue with converting this code to C in cover
> letter: how to make compiler to generate 32-bit code for a specific
> function or translation unit, without breaking linking afterwards (-m32
> break it).

Have you tried putting it into a separate .c file, and building it 32-bit?

I think arch/x86/entry/vdso/Makefile contains an example of how to build 32-bit 
code even on 64-bit kernels.

Thanks,

	Ingo

  parent reply	other threads:[~2017-04-11 11:28 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-06 14:00 [PATCH 0/8] x86: 5-level paging enabling for v4.12, Part 4 Kirill A. Shutemov
2017-04-06 14:00 ` Kirill A. Shutemov
2017-04-06 14:00 ` [PATCH 1/8] x86/boot/64: Rewrite startup_64 in C Kirill A. Shutemov
2017-04-06 14:00   ` Kirill A. Shutemov
2017-04-06 14:01 ` [PATCH 2/8] x86/boot/64: Rename init_level4_pgt and early_level4_pgt Kirill A. Shutemov
2017-04-06 14:01 ` [PATCH 3/8] x86/boot/64: Add support of additional page table level during early boot Kirill A. Shutemov
2017-04-06 14:01   ` Kirill A. Shutemov
2017-04-11  7:02   ` Ingo Molnar
2017-04-11  7:02     ` Ingo Molnar
2017-04-11 10:51     ` Kirill A. Shutemov
2017-04-11 10:51       ` Kirill A. Shutemov
2017-04-11 11:28       ` Ingo Molnar [this message]
2017-04-11 11:28         ` Ingo Molnar
2017-04-11 11:46         ` Kirill A. Shutemov
2017-04-11 11:46           ` Kirill A. Shutemov
2017-04-11 14:09           ` Andi Kleen
2017-04-12 10:18             ` Kirill A. Shutemov
2017-04-17 10:32               ` Ingo Molnar
2017-04-17 10:32                 ` Ingo Molnar
2017-04-18  8:59                 ` Kirill A. Shutemov
2017-04-18  8:59                   ` Kirill A. Shutemov
2017-04-18 10:15                   ` Kirill A. Shutemov
2017-04-18 11:10                     ` Kirill A. Shutemov
2017-04-18 11:10                       ` Kirill A. Shutemov
2017-04-06 14:01 ` [PATCH 4/8] x86/mm: Add sync_global_pgds() for configuration with 5-level paging Kirill A. Shutemov
2017-04-06 14:01   ` Kirill A. Shutemov
2017-04-06 14:01 ` [PATCH 5/8] x86/mm: Make kernel_physical_mapping_init() support " Kirill A. Shutemov
2017-04-06 14:01   ` Kirill A. Shutemov
2017-04-06 14:01 ` [PATCH 6/8] x86/mm: Add support for 5-level paging for KASLR Kirill A. Shutemov
2017-04-06 14:01   ` Kirill A. Shutemov
2017-04-06 14:01 ` [PATCH 7/8] x86: Enable 5-level paging support Kirill A. Shutemov
2017-04-06 14:01   ` Kirill A. Shutemov
2017-04-06 14:52   ` Juergen Gross
2017-04-06 15:24     ` Kirill A. Shutemov
2017-04-06 15:56       ` Juergen Gross
2017-04-06 14:01 ` [PATCH 8/8] x86/mm: Allow to have userspace mappings above 47-bits Kirill A. Shutemov
2017-04-06 14:01   ` Kirill A. Shutemov
2017-04-06 18:43   ` Dmitry Safonov
2017-04-06 19:15     ` Dmitry Safonov
2017-04-06 23:21       ` Kirill A. Shutemov
2017-04-06 23:24         ` [PATCHv2 " Kirill A. Shutemov
2017-04-06 23:24           ` Kirill A. Shutemov
2017-04-07 11:32           ` Dmitry Safonov
2017-04-07 15:44             ` [PATCHv3 " Kirill A. Shutemov
2017-04-07 16:37               ` Dmitry Safonov
2017-04-13 11:30             ` [PATCHv4 0/9] x86: 5-level paging enabling for v4.12, Part 4 Kirill A. Shutemov
2017-04-13 11:30               ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 1/9] x86/asm: Fix comment in return_from_SYSCALL_64 Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 2/9] x86/boot/64: Rewrite startup_64 in C Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 3/9] x86/boot/64: Rename init_level4_pgt and early_level4_pgt Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 4/9] x86/boot/64: Add support of additional page table level during early boot Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 5/9] x86/mm: Add sync_global_pgds() for configuration with 5-level paging Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 6/9] x86/mm: Make kernel_physical_mapping_init() support " Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 7/9] x86/mm: Add support for 5-level paging for KASLR Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 8/9] x86: Enable 5-level paging support Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-13 11:30               ` [PATCHv4 9/9] x86/mm: Allow to have userspace mappings above 47-bits Kirill A. Shutemov
2017-04-13 11:30                 ` Kirill A. Shutemov
2017-04-07 10:06         ` [PATCH 8/8] " Dmitry Safonov
2017-04-07 13:35   ` Anshuman Khandual
2017-04-07 13:35     ` Anshuman Khandual
2017-04-07 15:59     ` Kirill A. Shutemov
2017-04-07 15:59       ` Kirill A. Shutemov
2017-04-07 16:09       ` hpa
2017-04-07 16:09         ` hpa
2017-04-07 16:20         ` Kirill A. Shutemov
2017-04-12 10:41       ` Michael Ellerman
2017-04-12 11:11         ` Kirill A. Shutemov
2017-04-12 11:11           ` Kirill A. Shutemov

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