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From: ebiederm@xmission.com (Eric W. Biederman)
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Haren Myneni <hbabu@us.ibm.com>,
	Simon Horman <horms@verge.net.au>,
	Yinghai Lu <yinghai@kernel.org>,
	kexec@lists.infradead.org, Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH 3/8] add mem64_min/max control
Date: Sat, 17 Nov 2012 21:00:08 -0800	[thread overview]
Message-ID: <87haonqzdz.fsf@xmission.com> (raw)
In-Reply-To: <50A86A4D.8090503@zytor.com> (H. Peter Anvin's message of "Sat, 17 Nov 2012 20:55:41 -0800")

"H. Peter Anvin" <hpa@zytor.com> writes:

> On 11/17/2012 08:47 PM, Eric W. Biederman wrote:
>>>
>>> I don't think that is feasible; we need access to this structure
>>> extremely early.  I think if you're using the 64-bit entry point it
>>> has to be an entry condition that those structures are mapped.  It
>>> simply becomes a precondition for using the 64-bit entry point.
>>
>> 64bit purgatory coming from kexec should be running with a page table
>> that identity maps everything loaded by kexec and in practice all of
>> memory.
>>
>> We should still be using that page table when we enter the new kernel.
>>
>> However then the 64bit kernel switches to it's own page tables.
>>
>> So after that point we potentially need early_ioremap, because the
>> kernel's page tables may not have covered the boot_params.  Certainly we
>> need to do something to ensure the kernels page table covers boot_params.
>>
>
> The easy way to fix that is to do what we do on 32 bits: we copy it
> into the bss before we turn paging on (the 64-bit equivalent is before
> we switch to the new page tables.)  That way we know where it is, at
> least for the bounded-size data items.

Whatever works.  It sounds like six of one half a dozen of the other to
me.  Last I looked early_ioremap works as soon as paging is enabled on
x86_64.

Eric

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  reply	other threads:[~2012-11-18  5:01 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-11-16 23:04 [PATCH 0/8] kexec: put bzImage and ramdisk above 4G for x86 64bit Yinghai Lu
2012-11-16 23:04 ` [PATCH 1/8] Add min/max macro Yinghai Lu
2012-11-16 23:04 ` [PATCH 2/8] x86: add boot header member for version 2.12 Yinghai Lu
2012-11-16 23:04 ` [PATCH 3/8] add mem64_min/max control Yinghai Lu
2012-11-17  6:18   ` Eric W. Biederman
2012-11-17  7:06     ` Yinghai Lu
2012-11-17  8:25       ` Eric W. Biederman
2012-11-17 20:04         ` Yinghai Lu
2012-11-17 20:41           ` H. Peter Anvin
2012-11-17 20:51             ` Yinghai Lu
2012-11-17 20:54               ` H. Peter Anvin
2012-11-18  0:44           ` Yinghai Lu
2012-11-18  4:34             ` H. Peter Anvin
2012-11-18  4:47               ` Eric W. Biederman
2012-11-18  4:55                 ` H. Peter Anvin
2012-11-18  5:00                   ` Eric W. Biederman [this message]
2012-11-18  5:14                     ` H. Peter Anvin
2012-11-18  4:56                 ` Yinghai Lu
2012-11-18  5:20                   ` Eric W. Biederman
2012-11-18  5:35                     ` Yinghai Lu
2012-11-18  5:39                       ` Yinghai Lu
2012-11-18  5:58                         ` Yinghai Lu
2012-11-18  6:11                           ` Eric W. Biederman
2012-11-18  6:32                             ` Yinghai Lu
2012-11-18  6:38                             ` Yinghai Lu
2012-11-18  6:50                               ` Eric W. Biederman
2012-11-18  6:53                                 ` Yinghai Lu
2012-11-18  7:18                                   ` Yinghai Lu
2012-11-18 10:38                                     ` Eric W. Biederman
2012-11-19  3:02                                       ` [PATCH 0/6] kexec: put bzImage and ramdisk above 4G for x86 64bit Yinghai Lu
2012-11-19  3:02                                         ` [PATCH 1/6] kexec, x86: add boot header member for version 2.12 Yinghai Lu
2012-11-19  3:02                                         ` [PATCH 2/6] kexec: don't die during buffer finding Yinghai Lu
2012-11-19  3:02                                         ` [PATCH 3/6] kexec, x86: put ramdisk high for 64bit bzImage Yinghai Lu
2012-11-19  3:02                                         ` [PATCH 4/6] kexec, x86: set ext_cmd_line_ptr when boot_param is put high Yinghai Lu
2012-11-19  3:02                                         ` [PATCH 5/6] kexec, x86: Make x64_64 purgatory relocatable above 4G Yinghai Lu
2012-11-19  3:02                                         ` [PATCH 6/6] kexec, x86_64: put 64bit bzImage high Yinghai Lu
2012-11-19  3:04                                       ` [PATCH v2 0/6] kexec: put bzImage and ramdisk above 4G for x86 64bit Yinghai Lu
2012-11-19  3:04                                         ` [PATCH v2 1/6] kexec, x86: add boot header member for version 2.12 Yinghai Lu
2012-11-19  3:04                                         ` [PATCH v2 2/6] kexec: don't die during buffer finding Yinghai Lu
2012-11-19 17:05                                           ` Eric W. Biederman
2012-11-19  3:04                                         ` [PATCH v2 3/6] kexec, x86: put ramdisk high for 64bit bzImage Yinghai Lu
2012-11-19 17:20                                           ` Eric W. Biederman
2012-11-19  3:04                                         ` [PATCH v2 4/6] kexec, x86: set ext_cmd_line_ptr when boot_param is put high Yinghai Lu
2012-11-19 17:22                                           ` Eric W. Biederman
2012-11-19  3:04                                         ` [PATCH v2 5/6] kexec, x86: Make x64_64 purgatory relocatable above 4G Yinghai Lu
2012-11-19  3:04                                         ` [PATCH v2 6/6] kexec, x86_64: put 64bit bzImage high Yinghai Lu
2012-11-19 17:28                                           ` Eric W. Biederman
2012-11-19 17:04                                         ` [PATCH v2 0/6] kexec: put bzImage and ramdisk above 4G for x86 64bit Eric W. Biederman
2012-11-18  6:24                         ` [PATCH 3/8] add mem64_min/max control H. Peter Anvin
2012-11-18  6:23                     ` H. Peter Anvin
2012-11-18  6:44                       ` Eric W. Biederman
2012-11-16 23:04 ` [PATCH 4/8] Move out mem_min/max checking in locate_hole Yinghai Lu
2012-11-16 23:04 ` [PATCH 5/8] seperate checking 64bit mem range Yinghai Lu
2012-11-16 23:04 ` [PATCH 6/8] debug print out for add_buf Yinghai Lu
2012-11-16 23:04 ` [PATCH 7/8] x86: put ramdisk high for 64bit bzImage Yinghai Lu
2012-11-16 23:04 ` [PATCH 8/8] x86: put 64bit bzImage high Yinghai Lu
2012-11-17  6:33   ` Eric W. Biederman
     [not found]     ` <CAE9FiQWJaT9yfdV0rgV-5rM=BR4eX8sr+a99g8Ggf-+YkD8qgQ@mail.gmail.com>
2012-11-17  8:43       ` Eric W. Biederman
2012-11-19 21:00 ` [PATCH 0/8] kexec: put bzImage and ramdisk above 4G for x86 64bit Vivek Goyal
2012-11-19 22:34   ` Yinghai Lu

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