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What exactly is a Legacy ROM option in the boot section of my BIOS

Last response: in Motherboards
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October 12, 2012 8:14:10 PM

I am thinking about building a A10-5800k machine using a Gigabyte GA_F2a85x-UP4 motherboard. I have been looking at the manual before buying the motherboard. From the internet I learned that a Legacy device is a device that needs a jumper to modified it or it won't work.
As I am reading my manual, under boot section, do I want to enable Legacy Only for storage boot? I thought I want everything in UEFI. What does it mean if I do set it to UEFI?
Under the same Boot section, Display Boot Option Control, I also thought enable UEFI only. Is there a reason I shouldn't?

Thanks
Eddy
October 12, 2012 8:24:57 PM

Legacy Only storage boot would disable RAID and AHCI (not the best idea when you have a modern OS).

You can enable UEFI only if you're running Windows 7 or 8 or something, as only legacy OS require legacy EFI BIOS.
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October 12, 2012 9:47:37 PM

thanks for the quick reply,
my intention is to use AHCI with a SSD. I guess that means I will enable the UEFI in the boot storage section.
what about the display option in the boot options?
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October 12, 2012 9:56:54 PM

You don't have to make it UEFI-only, it won't help, but it won't hurt either. I would say just leave it alone.
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a c 168 V Motherboard
October 12, 2012 10:00:23 PM

watchman323 said:
I am thinking about building a A10-5800k machine using a Gigabyte GA_F2a85x-UP4 motherboard. I have been looking at the manual before buying the motherboard. From the internet I learned that a Legacy device is a device that needs a jumper to modified it or it won't work.
As I am reading my manual, under boot section, do I want to enable Legacy Only for storage boot? I thought I want everything in UEFI. What does it mean if I do set it to UEFI?
Under the same Boot section, Display Boot Option Control, I also thought enable UEFI only. Is there a reason I shouldn't?

Thanks
Eddy


"Legacy ROM" refers to the format of the OPROM on the storage controller. There are two firmware standards for PCs, the legacy BIOS standard and the new EFI/UEFI standard. These are standards which specify behaviour, not implementations which must be handled by the manufacturer. Since firmware is minimalistic by design, the motherboard firmware only contains code to initialize the devices on the motherboard. Both standards specify a method of loading a BIOS/EFI compatible OPROM (Option ROM) from an external device such as a VGA adapter, dedicated RAID controller, or add-in storage controller.

Since the specification for BIOS and EFI are different it would be possible to mismatch a BIOS OPROM with an EFI firmware. EFI contains the ability to load and execute BIOS compatible devices, but BIOS does not contain the ability to load EFI devices. Thus, many device manufacturers ship devices with two OPROMs, one which is BIOS compatible and called the "Legacy ROM" and one that is EFI compatible. If the OPROM format is set to "Legacy ROM" it will always use the legacy OM on the device, if it is set to "EFI Compatible" it will use the newer EFI ROM if one is present and the Legacy ROM if one is not.

EFI ROMs are necessary for some of the new firmware level security features as well as for proper EFI boot sequences. For example, installing Windows from an optical disk which is attached to a non-EFI compatible storage controller can cause problems if it is installed to a storage controller which has an EFI compatible ROM.
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August 27, 2013 2:51:00 AM

Pinhedd said:
watchman323 said:
I am thinking about building a A10-5800k machine using a Gigabyte GA_F2a85x-UP4 motherboard. I have been looking at the manual before buying the motherboard. From the internet I learned that a Legacy device is a device that needs a jumper to modified it or it won't work.
As I am reading my manual, under boot section, do I want to enable Legacy Only for storage boot? I thought I want everything in UEFI. What does it mean if I do set it to UEFI?
Under the same Boot section, Display Boot Option Control, I also thought enable UEFI only. Is there a reason I shouldn't?

Thanks
Eddy


"Legacy ROM" refers to the format of the OPROM on the storage controller. There are two firmware standards for PCs, the legacy BIOS standard and the new EFI/UEFI standard. These are standards which specify behaviour, not implementations which must be handled by the manufacturer. Since firmware is minimalistic by design, the motherboard firmware only contains code to initialize the devices on the motherboard. Both standards specify a method of loading a BIOS/EFI compatible OPROM (Option ROM) from an external device such as a VGA adapter, dedicated RAID controller, or add-in storage controller.

Since the specification for BIOS and EFI are different it would be possible to mismatch a BIOS OPROM with an EFI firmware. EFI contains the ability to load and execute BIOS compatible devices, but BIOS does not contain the ability to load EFI devices. Thus, many device manufacturers ship devices with two OPROMs, one which is BIOS compatible and called the "Legacy ROM" and one that is EFI compatible. If the OPROM format is set to "Legacy ROM" it will always use the legacy OM on the device, if it is set to "EFI Compatible" it will use the newer EFI ROM if one is present and the Legacy ROM if one is not.

EFI ROMs are necessary for some of the new firmware level security features as well as for proper EFI boot sequences. For example, installing Windows from an optical disk which is attached to a non-EFI compatible storage controller can cause problems if it is installed to a storage controller which has an EFI compatible ROM.


I have read it all slowly to understand... But I have a question..
So I made an UEFI Installation for windows 8 and now my system boots up UEFI in windows 8. But in bios I have
CSM: ON (Always)
----
storage boot control option: legacy mode
----

its related to the storage contoller (I guess like chipset sata controller) and do I have to change it to UEFI ? because I boot windows 8 in uefi or leave it as it is ?

Im so confused...
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a c 168 V Motherboard
August 27, 2013 8:00:32 AM

X-FI said:
Pinhedd said:
watchman323 said:
I am thinking about building a A10-5800k machine using a Gigabyte GA_F2a85x-UP4 motherboard. I have been looking at the manual before buying the motherboard. From the internet I learned that a Legacy device is a device that needs a jumper to modified it or it won't work.
As I am reading my manual, under boot section, do I want to enable Legacy Only for storage boot? I thought I want everything in UEFI. What does it mean if I do set it to UEFI?
Under the same Boot section, Display Boot Option Control, I also thought enable UEFI only. Is there a reason I shouldn't?

Thanks
Eddy


"Legacy ROM" refers to the format of the OPROM on the storage controller. There are two firmware standards for PCs, the legacy BIOS standard and the new EFI/UEFI standard. These are standards which specify behaviour, not implementations which must be handled by the manufacturer. Since firmware is minimalistic by design, the motherboard firmware only contains code to initialize the devices on the motherboard. Both standards specify a method of loading a BIOS/EFI compatible OPROM (Option ROM) from an external device such as a VGA adapter, dedicated RAID controller, or add-in storage controller.

Since the specification for BIOS and EFI are different it would be possible to mismatch a BIOS OPROM with an EFI firmware. EFI contains the ability to load and execute BIOS compatible devices, but BIOS does not contain the ability to load EFI devices. Thus, many device manufacturers ship devices with two OPROMs, one which is BIOS compatible and called the "Legacy ROM" and one that is EFI compatible. If the OPROM format is set to "Legacy ROM" it will always use the legacy OM on the device, if it is set to "EFI Compatible" it will use the newer EFI ROM if one is present and the Legacy ROM if one is not.

EFI ROMs are necessary for some of the new firmware level security features as well as for proper EFI boot sequences. For example, installing Windows from an optical disk which is attached to a non-EFI compatible storage controller can cause problems if it is installed to a storage controller which has an EFI compatible ROM.


I have read it all slowly to understand... But I have a question..
So I made an UEFI Installation for windows 8 and now my system boots up UEFI in windows 8. But in bios I have
CSM: ON (Always)
----
storage boot control option: legacy mode
----

its related to the storage contoller (I guess like chipset sata controller) and do I have to change it to UEFI ? because I boot windows 8 in uefi or leave it as it is ?

Im so confused...


When the storage boot control option is set to "Legacy Mode" it will be able to boot from all bootable devices that are attached to the system, regardless of whether or not they actually have bootable volumes on them. This requires the firmware to scan all devices in the boot priority for a functional MBR or GPT until one is found. The UEFI mode scans for only GPT with bootable volumes and will list in the boot priority only those that are found. Thus, in UEFI mode,it's unlikely that anyone will ever see the good old "boot device not found, please insert system disk and press enter"
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