Re: [Xen-devel] [PATCH v6 01/22] arm/acpi: Estimate memory required for acpi/efi tables

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.03.16 at 19:44, <julien.grall@xxxxxxx> wrote:
> On 17/03/16 09:40, Shannon Zhao wrote:
>> --- /dev/null
>> +++ b/xen/arch/arm/efi/efi-dom0.c
>> @@ -0,0 +1,50 @@
>> +/*
>> + *  efi-dom0.c - Domain0 EFI Boot Support
>> + *
>> + *  Copyright (C) 2016 Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>> + *
>> + * 
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; either version 2 of the License, or
>> + *  (at your option) any later version.
>> + *
>> + *  This program is distributed in the hope that it will be useful,
>> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + *  GNU General Public License for more details.
>> + *
>> + *  You should have received a copy of the GNU General Public License
>> + *  along with this program; If not, see <http://www.gnu.org/licenses/>.
>> + *
>> + * 
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +
>> +#include "efi.h"
>> +#include "efi-dom0.h"
>> +#include <asm/setup.h>
>> +#include <asm/acpi.h>
>> +
>> +struct meminfo __initdata acpi_mem;
> 
> I'm worry about sharing data between the EFI stub and Xen. On ARM, the 
> EFI stub is completely independent. Once it has finished to execute, it 
> will call xen as if it runs without UEFI.
> 
> This means that BSS will be zeroed. I would have expect to see acpi_mem 
> residing in BSS. So I'm wondering how this can work.

The __initdata annotation makes it a member of .init.data instead
of the expected .bss.

Jan


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