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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Daniel Kiper <daniel.kiper@oracle.com>
Cc: 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,
	jbeulich@suse.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: Fri, 16 Sep 2016 16:43:21 -0400	[thread overview]
Message-ID: <20160916204320.GA18677@char.us.oracle.com> (raw)
In-Reply-To: <1473711511-11931-2-git-send-email-daniel.kiper@oracle.com>

On Mon, Sep 12, 2016 at 10:18:16PM +0200, Daniel Kiper wrote:
> Currently ELF end of image address is calculated using first line from
> "nm -nr xen/xen-syms" output. However, today usually it contains random
> symbol address not related to end of image in any way. So, it looks

Weird. The -n says:

"  -n
       -v
       --numeric-sort
           Sort symbols numerically by their addresses, rather than alphabetically by their names.
"

And you are right. It is ignoring it:

[konrad@char xen]$ nm -nr xen/xen-syms| sort | head -1
ffff82d080000000 T __image_base__
[konrad@char xen]$ nm -nr xen/xen-syms | head -1
ffff82d08033d000 B efi

[konrad@char xen]$ nm -nr xen/xen-syms| sort | tail -5
ffff82d08033cb00 B _end
ffff82d08033cb00 B __per_cpu_data_end
ffff82d08033d000 B __2M_rwdata_end
ffff82d08033d000 B efi
                 U _GLOBAL_OFFSET_TABLE_

> that for years that stuff have been working just by lucky coincidence.
> Hence, it have to be changed to something more reliable. So, let's take
> ELF end of image address by reading _end symbol address from nm output.
> 
> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com>
> ---
>  xen/arch/x86/Makefile |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
> index d3875c5..a4fe740 100644
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -91,7 +91,7 @@ endif
>  
>  $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
>  	./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TARGET) 0x100000 \
> -	`$(NM) -nr $(TARGET)-syms | head -n 1 | sed -e 's/^\([^ ]*\).*/0x\1/'`
> +		`$(NM) -nr $(TARGET)-syms | awk '$$3 == "_end" {print "0x"$$1}'`
>  

Something is off with your tabs/spaces.


I would also modify the arch/x86/xen.lds.S and put a comment
around _end = .; to mention this dependency - in case somebody adds some 
extra things after _end.


>  .PHONY: tests
>  tests:
> -- 
> 1.7.10.4
> 

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  reply	other threads:[~2016-09-16 20:43 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 [this message]
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
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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