Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [Xen-devel] [PATCH 2/3] x86/acpi: take rsdp address for boot
 params if available
To:     =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= <roger.pau@citrix.com>
Cc:     linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
        x86@kernel.org, corbet@lwn.net, rjw@rjwysocki.net,
        linux-acpi@vger.kernel.org, mingo@redhat.com, hpa@zytor.com,
        boris.ostrovsky@oracle.com, tglx@linutronix.de, lenb@kernel.org
References: <20171128094400.25955-1-jgross@suse.com>
 <20171128094400.25955-3-jgross@suse.com>
 <20171128101834.fmiqygqpfh6wxrvv@MacBook-Pro-de-Roger.local>
From:   Juergen Gross <jgross@suse.com>
Message-ID: <072e88ef-dd61-8b7d-026a-5966b13ffed9@suse.com>
Date:   Tue, 28 Nov 2017 11:30:15 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.4.0
MIME-Version: 1.0
In-Reply-To: <20171128101834.fmiqygqpfh6wxrvv@MacBook-Pro-de-Roger.local>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 28/11/17 11:18, Roger Pau Monné wrote:
> On Tue, Nov 28, 2017 at 10:43:59AM +0100, Juergen Gross wrote:
>> In case the rsdp address in struct boot_params is specified don't try
>> to find the table by searching, but take the address directly as set
>> by the boot loader.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>>  drivers/acpi/osl.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
>> index 3bb46cb24a99..3b25e2ad7d75 100644
>> --- a/drivers/acpi/osl.c
>> +++ b/drivers/acpi/osl.c
>> @@ -45,6 +45,10 @@
>>  #include <linux/uaccess.h>
>>  #include <linux/io-64-nonatomic-lo-hi.h>
>>  
>> +#ifdef CONFIG_X86
>> +#include <asm/setup.h>
>> +#endif
>> +
>>  #include "internal.h"
>>  
>>  #define _COMPONENT		ACPI_OS_SERVICES
>> @@ -195,6 +199,10 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
>>  	if (acpi_rsdp)
>>  		return acpi_rsdp;
>>  #endif
>> +#ifdef CONFIG_X86
>> +	if (boot_params.hdr.acpi_rsdp_addr)
>> +		return boot_params.hdr.acpi_rsdp_addr;
>> +#endif
> 
> I'm struggling to figure out how was PVH getting the RSDP previously,
> because that should be removed now that it's in the zero-page.

I don't think it should be removed, because this was the legacy case
(searching through memory). It was pure luck that Xen put it at the
right location.


Juergen

From 1585306657308184649@xxx Tue Nov 28 10:50:42 +0000 2017
X-GM-THRID: 1585302521989218363
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread