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From: "Jan Beulich" <JBeulich@suse.com>
To: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Juergen Gross <JGross@suse.com>,
	sstabellini@kernel.org, andrew.cooper3@citrix.com,
	cardoe@cardoe.com, pgnet.dev@gmail.com, ning.sun@intel.com,
	david.vrabel@citrix.com, xen-devel@lists.xenproject.org,
	qiaowei.ren@intel.com, gang.wei@intel.com, fu.wei@linaro.org
Subject: Re: [PATCH v6 01/15] x86: properly calculate ELF end of image address
Date: Tue, 20 Sep 2016 07:28:58 -0600	[thread overview]
Message-ID: <57E155BA0200007800110A3F@prv-mh.provo.novell.com> (raw)
In-Reply-To: <20160920114329.GB28753@olila.local.net-space.pl>

>>> On 20.09.16 at 13:43, <daniel.kiper@oracle.com> wrote:
> On Mon, Sep 19, 2016 at 08:52:02AM -0600, Jan Beulich wrote:
>> >>> On 19.09.16 at 15:56, <daniel.kiper@oracle.com> wrote:
>> > On Mon, Sep 19, 2016 at 05:14:07AM -0600, Jan Beulich wrote:
>> >> >>> On 16.09.16 at 22:43, <konrad.wilk@oracle.com> wrote:
>> >> > On Mon, Sep 12, 2016 at 10:18:16PM +0200, Daniel Kiper wrote:
>> >> In particular
>> >> I can't see why __2M_rwdata_end (aliased to efi) does not relate to
>> >> the intended image end. Once we switch back to using large pages
>> >> even when not using xen.efi I'd even question whether preferring
>> >> _end over __2M_rwdata_end is actually correct.
>> >
>> > This is good question. I was thinking about that after posting v6. It seems
>> > that from image POV _end is correct. However, taking into account that Xen
>> > image mapping covers 16 MiB then I think we should use __2M_rwdata_end (or
>> > define __end_of_image__ symbol equal to __2M_rwdata_end). This way boot
>> > loader will allocate memory region for Xen image later covered properly by
>> > mapping, nothing will be put in memory immediately after the Xen image and
>> > later incorrectly mapped as Xen image.
> 
> Current xen image p_memsz does not end at 16 MiB. It seems to me that this is
> incorrect. Should I fix it? It looks that we just have to move out .pad of
> #ifdef EFI. Are you OK with it?

Just to emphasize again: I'm okay with any fix which actually fixes
something. I continue to be unconvinced there is something that
actually needs fixing. So as long as you can properly explain what
is wrong, I won't stand in the way of your change going in. For the
case here this means - if the value is e.g. off by a few bytes, then
I don't see an issue. This 16Mb boundary isn't a hard one anyway.
If otoh the value is off by an arbitrary amount, which just happens
to be small enough in most cases, then I do see a need for a change.

Jan


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  reply	other threads:[~2016-09-20 13:29 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-12 20:18 [PATCH v6 00/15] x86: multiboot2 protocol support Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 01/15] x86: properly calculate ELF end of image address Daniel Kiper
2016-09-16 20:43   ` Konrad Rzeszutek Wilk
2016-09-19 11:14     ` Jan Beulich
2016-09-19 13:56       ` Daniel Kiper
2016-09-19 14:52         ` Jan Beulich
2016-09-20 11:43           ` Daniel Kiper
2016-09-20 13:28             ` Jan Beulich [this message]
2016-09-20 18:00           ` Daniel Kiper
2016-09-21  9:37             ` Jan Beulich
2016-09-22 11:45               ` Daniel Kiper
2016-09-22 12:02                 ` Jan Beulich
2016-09-19 11:18     ` Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 02/15] x86/boot/reloc: create generic alloc and copy functions Daniel Kiper
2016-09-19 11:23   ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 03/15] x86/boot/reloc: rename some variables and rearrange code a bit Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 04/15] x86: add multiboot2 protocol support Daniel Kiper
2016-09-19 11:42   ` Jan Beulich
2016-09-21  8:56     ` Daniel Kiper
2016-09-21  9:41       ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 05/15] efi: create efi_enabled() Daniel Kiper
2016-09-19 11:58   ` Jan Beulich
2016-09-19 14:27     ` Daniel Kiper
2016-09-19 14:31       ` Wei Liu
2016-09-19 14:57       ` Jan Beulich
2016-09-19 15:38         ` Daniel Kiper
2016-09-19 16:00           ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 06/15] x86: allow EFI reboot method neither on EFI platforms Daniel Kiper
2016-09-19 12:01   ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 07/15] efi: build xen.gz with EFI code Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 08/15] x86/efi: create new early memory allocator Daniel Kiper
2016-09-19 12:12   ` Jan Beulich
2016-09-19 15:04     ` Daniel Kiper
2016-09-19 15:17       ` Jan Beulich
2016-09-20  9:45         ` Daniel Kiper
2016-09-20  9:57           ` Jan Beulich
2016-09-20 10:52             ` Daniel Kiper
2016-09-20 13:46               ` Jan Beulich
2016-09-20 18:45                 ` Daniel Kiper
2016-09-21  9:42                   ` Jan Beulich
2016-09-22 10:52                     ` Daniel Kiper
2016-09-22 11:25                       ` Jan Beulich
2016-09-22 12:07                         ` Daniel Kiper
2016-09-22 13:12                           ` Jan Beulich
2016-09-22 17:07                           ` Julien Grall
2016-09-23 10:50                             ` Daniel Kiper
2016-09-23 11:07                               ` Julien Grall
2016-09-23 11:35                                 ` Daniel Kiper
2016-09-23 11:42                                   ` Julien Grall
2016-09-23 11:53                                     ` Daniel Kiper
2016-09-23 14:10                                   ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 09/15] x86: add multiboot2 protocol support for EFI platforms Daniel Kiper
2016-09-19 12:29   ` Jan Beulich
2016-09-19 15:18     ` Daniel Kiper
2016-09-19 15:28       ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 10/15] x86/boot: implement early command line parser in C Daniel Kiper
2016-09-19 12:47   ` Jan Beulich
2016-09-19 15:27     ` Daniel Kiper
2016-09-19 16:03       ` Jan Beulich
2016-09-20  9:49         ` Daniel Kiper
2016-09-20 10:05           ` Jan Beulich
2016-09-20 11:31             ` Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 11/15] x86: change default load address from 1 MiB to 2 MiB Daniel Kiper
2016-09-19 12:54   ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 12/15] x86/setup: use XEN_IMG_OFFSET instead of Daniel Kiper
2016-09-19 13:00   ` Jan Beulich
2016-09-12 20:18 ` [PATCH v6 13/15] x86: make Xen early boot code relocatable Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 14/15] x86/boot: rename sym_phys() to sym_offs() Daniel Kiper
2016-09-12 20:18 ` [PATCH v6 15/15] x86: add multiboot2 protocol support for relocatable images Daniel Kiper

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