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From: Julien Grall <julien.grall@citrix.com>
To: Ian Campbell <ian.campbell@citrix.com>,
	Shannon Zhao <shannon.zhao@linaro.org>,
	Shannon Zhao <zhaoshenglong@huawei.com>,
	xen-devel <xen-devel@lists.xen.org>
Cc: Hangaohuai <hangaohuai@huawei.com>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	andrew@fubar.geek.nz,
	"Huangpeng (Peter)" <peter.huangpeng@huawei.com>,
	Stefano Stabellini <stefano.stabellini@citrix.com>,
	David Vrabel <david.vrabel@citrix.com>,
	Jan Beulich <jbeulich@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Parth Dixit <parth.dixit@linaro.org>,
	Christoffer Dall <christoffer.dall@linaro.org>,
	Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: Design doc of adding ACPI support for arm64 on Xen - version 5
Date: Wed, 2 Sep 2015 14:48:01 +0100	[thread overview]
Message-ID: <55E6FE11.3060401@citrix.com> (raw)
In-Reply-To: <1441200364.26292.190.camel@citrix.com>

On 02/09/15 14:26, Ian Campbell wrote:
>>>> I think the problem is how you reserved this region in the EFI memory
>>>> table. From what I saw, you marked this new memory with EFI_MEMORY_WB
>>>> (which means that the region can be usable by Linux).
>>>>
>>> Yes, I mark it with EFI_MEMORY_WB. Is this right?
>>
>> I would say no, but it's only because I looked at the kernel code 
>> quickly.
>>
>> You have to looks how ACPI region/UEFI tables are described in the host
>> EFI memory map and mimicking for the DOM0 EFI memory map.
> 
> Surely it is the type (EfiACPIReclaimMemory, EfiACPIMemoryNVS etc) and not
> the mapping attributes which should control whether an OS considers a
> region usable? At least until the OS is done parsing tables neither of
> those are usable (which implies we want NVS as our type, unless the memory
> is intended to be reclaimed by dom0, implying it should own it).

It looks like that Linux on ARM64 is considering any region with
EFI_MEMORY_WB set as normal RAM and will try to add as System RAM (see
reserve_regions in arch/arm64/kernel/efi.c).

At the same time, having WB set for a region that should be read-only
looks like wrong to me.

Regards,

-- 
Julien Grall

  reply	other threads:[~2015-09-02 13:48 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-28  9:45 Design doc of adding ACPI support for arm64 on Xen - version 5 Shannon Zhao
2015-08-28 12:55 ` Julien Grall
2015-08-29  1:00   ` Shannon Zhao
2015-08-31  7:33     ` Jan Beulich
2015-08-31 11:44     ` Julien Grall
2015-08-31 12:03       ` Shannon Zhao
2015-08-31 12:34         ` Julien Grall
2015-09-01  4:12           ` Shannon Zhao
2015-09-01 11:28             ` Julien Grall
2015-09-01 12:35               ` Shannon Zhao
2015-09-01 13:40                 ` Julien Grall
2015-09-01 14:03                   ` Jan Beulich
2015-09-01 14:20                     ` Julien Grall
2015-09-02  6:02                   ` Shannon Zhao
2015-09-02  8:41                     ` Jan Beulich
2015-09-02  9:18                       ` Christoffer Dall
2015-09-02 11:15                         ` Julien Grall
2015-09-02  9:25                       ` Shannon Zhao
2015-09-02 12:30                         ` Jan Beulich
2015-09-02 11:09                     ` Julien Grall
2015-09-02 12:02                       ` Shannon Zhao
2015-09-02 12:52                         ` Julien Grall
2015-09-02 13:26                           ` Ian Campbell
2015-09-02 13:48                             ` Julien Grall [this message]
2015-09-02 13:54                               ` Ian Campbell
2015-09-02 13:57                                 ` Christoffer Dall
2015-09-02 15:27                                   ` Leif Lindholm
2015-09-02 15:37                                     ` Ard Biesheuvel
2015-09-02 14:00                               ` Jan Beulich
2015-09-02 12:58           ` Ian Campbell
2015-08-28 15:06 ` Jan Beulich
2015-08-29  1:29   ` Shannon Zhao
2015-08-31  7:39     ` Jan Beulich
2015-08-31  8:51       ` Shannon Zhao
2015-08-31  9:40         ` Jan Beulich
2015-08-31 11:31           ` Shannon Zhao
2015-08-31 11:46             ` Jan Beulich
2015-09-02 12:54           ` Ian Campbell
2015-09-02 13:59             ` Shannon Zhao
2015-09-02 14:24               ` Ian Campbell
2015-09-02 12:18 ` Ian Campbell
2015-09-07  3:37   ` Shannon Zhao
2015-09-07 10:47     ` Stefano Stabellini

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