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 Post subject: [SOLVED] PCIe card hot plug capable
PostPosted: Mon Aug 16, 2021 6:01 am 
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While reading some pdf about PCI spec, I am reading that PCIe hot plug capable does exist.

Quote:
4.1. Enhanced Configuration Access Method Base Address

On PC-compatible systems, the enhanced configuration access mechanism allows PCI configuration space to be accessed using memory primitives rather than I/O-based primitives (CF8/CFC mechanism).
For PCI Express and PCI-X Mode 2 hierarchies on these systems, the memory mapped configuration access mechanism is the only way to access the extended configuration space (offsets 256-4095).

This section defines an ACPI-based mechanisms to communicate the memory mapped configuration space base address(es) used for Enhanced Configuration Access Mechanism (defined in PCI-X and PCI Express Local Bus Specifications) to the operating system:

 MCFG: An ACPI table-based mechanism that is used to communicate the memory mapped configuration space base addresses corresponding to the (non-hot removable) PCI Segment Groups and/or base address ranges within a PCI Segment Group available to the system at boot.
The memory mapped configuration space address ranges described exclusively through the table mechanism are considered to be non-relocatable and non-hot removable for the current boot.

 _CBA: An ACPI method that is used to report the Enhanced Configuration Access base address for any PCI Segment Groups and/or base address ranges within a PCI Segment group.
This allows run-time update for the hot added PCI components.

The MCFG table is only used to communicate the base addresses corresponding to the non-hot removable PCI Segment Groups available to the system at boot.
The _CBA method enables the system to describe the base address of the memory mapped configuration space for hot plug capable PCI Segment Groups.


And I can find a confirmation among Windows docs
https://docs.microsoft.com/en-us/window ... ss-devices

So, what are these PCI hot plug capable devices they are talking about because I know none

Maybe that https://downloads.dell.com/manuals/comm ... option.pdf

But not sure.


Last edited by Rukog on Mon Aug 16, 2021 8:42 am, edited 1 time in total.

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 Post subject: Re: PCIe card hot plug capable
PostPosted: Mon Aug 16, 2021 7:07 am 
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The only thing I can think of is M.2 cards maybe. Also, remember this from the forum rules
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 Post subject: Re: PCIe card hot plug capable
PostPosted: Mon Aug 16, 2021 8:42 am 
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M.2 isn't really designed for hot plug, but U.2 is. Hot plug U.2 drive bays are pretty common in server hardware.

If you look at the most expensive high-end servers, you can find ordinary PCIe slots and cards that support hot plug too.


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 Post subject: Re: [SOLVED] PCIe card hot plug capable
PostPosted: Mon Aug 16, 2021 1:29 pm 
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Every Thunderbolt-capable mainboard can do PCIe hotplug. Thunderbolt simply exposes PCIe lanes over a different connector.

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