Question for memory type: EfiReservedMemoryType

Question for memory type: EfiReservedMemoryType

[Kirkendall, Garrett]

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 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/>

Re: Question for memory type: EfiReservedMemoryType

[Andrew Fish]

> 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/>
> 
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel

答复: Question for memory type: EfiReservedMemoryType

[Liu Pedroa]

According to ACPI 6.1  Spec :

Platform runtime firmware can use the AddressRangeReserved address range type to block out 
various addresses as not suitable for use by a programmable device. Some of the reasons a platform 
runtime firmware would do this are:
? The address range contains system ROM.
? The address range contains RAM in use by the ROM.
? The address range is in use by a memory-mapped system device.
? The address range is, for whatever reason, unsuitable for a standard device to use as a device 
memory space.
? The address range is within an NVRAM device where reads and writes to memory locations are 
no longer successful, that is, the device was worn out.








-----邮件原件-----
发件人: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] 代表 Kirkendall, Garrett
发送时间: 2017年2月17日 23:55
收件人: edk2-devel@lists.01.org
主题: [edk2] Question for memory type: EfiReservedMemoryType

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 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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