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From: Andrew Fish <afish@apple.com>
To: "Kirkendall, Garrett" <Garrett.Kirkendall@amd.com>
Cc: "edk2-devel@lists.01.org" <edk2-devel@lists.01.org>
Subject: Re: Question for memory type: EfiReservedMemoryType
Date: Fri, 17 Feb 2017 08:13:12 -0800	[thread overview]
Message-ID: <D000A972-7A99-4D9E-AD9B-75D98C8CB33D@apple.com> (raw)
In-Reply-To: <DM2PR12MB0154BB6BEC9F12022129884D855D0@DM2PR12MB0154.namprd12.prod.outlook.com>


> On Feb 17, 2017, at 7:55 AM, Kirkendall, Garrett <Garrett.Kirkendall@amd.com> wrote:
> 
> The UEFI spec says:
> EfiReservedMemoryType - Not usable.
> 
> Some people take this to mean that you should not use this memory type.  Some think it will mark the memory as unusable by UEFI or OS.
> 
> Could the spec be updated to be more precise as to the meaning?
> 
> As far as I can tell, the code will allocate memory of type EfiReservedMemoryType and will not use that memory.
> 

Garrett,

The UEFI Spec is written from an Option ROM (EFI Driver) and OS Loader point of view. Basically PI components (Platform Firmware in the ROM) can use the EfiReservedMemoryType. 

I've seen S3 and SMM code that allocates EfiReservedMemoryType to hide a memory region from the OS that does not require a virtual mapping. 

Thanks,

Andrew Fish

> Garrett Kirkendall
> SMTS Firmware Engineer | CTE
> 7171 Southwest Parkway, Austin, TX 78735 USA
> AMD   facebook<https://www.facebook.com/AMD>  |  amd.com<http://www.amd.com/>
> 
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  reply	other threads:[~2017-02-17 16:13 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-17 15:55 Question for memory type: EfiReservedMemoryType Kirkendall, Garrett
2017-02-17 16:13 ` Andrew Fish [this message]
2017-02-22  1:56 ` 答复: " Liu Pedroa

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