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Date: Tue, 03 Feb 2015 17:51:17 +0100
From: Laszlo Ersek <lersek@redhat.com>
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Subject: Re: [Qemu-devel] [RFC PATCH v2 09/11] hw/arm/virt-acpi-build:
	Generate XSDT table
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To: Igor Mammedov <imammedo@redhat.com>, Shannon Zhao <zhaoshenglong@huawei.com>
Cc: peter.maydell@linaro.org, hangaohuai@huawei.com, mst@redhat.com, a.spyridakis@virtualopensystems.com, claudio.fontana@huawei.com, qemu-devel@nongnu.org, peter.huangpeng@huawei.com, hanjun.guo@linaro.org, wanghaibin.wang@huawei.com, pbonzini@redhat.com, christoffer.dall@linaro.org

On 02/03/15 17:19, Igor Mammedov wrote:
> On Thu, 29 Jan 2015 16:37:11 +0800
> Shannon Zhao <zhaoshenglong@huawei.com> wrote:
> 
>> XDST points to other tables except FACS & DSDT.
> Is there any reason to use XSDT instead of RSDT?
> If ACPI tables are below 4Gb which probably would
> be the case then RSDT could be used just fine and
> we could share more code between x86 and ARM.
> 
> Laszlo,
> Do you know if OVMF allocates memory below 4G address range?

Yes, it does.

https://github.com/tianocore/edk2/blob/master/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c#L162

RSDT should suffice.

Thanks,
Laszlo