Kernel Newbies archive on
 help / color / Atom feed
From: Greg KH <>
To: Sadanand Warrier <>
Subject: Re: PCIe hotplug
Date: Thu, 13 Feb 2020 09:48:46 -0800
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, Feb 13, 2020 at 12:40:59PM -0500, Sadanand Warrier wrote:
> Hi
>    I had  question about PCIe hotplug. We have hardware that is connected
> to the host by means of two PCIe switches. i.e. the host sees a PCIe switch
> connected to one of its buses and on the far side of that switch another
> PCIe switch which has a PCIe device.
>    It is possible that this device does not train its host facing PCIe
> links before the server enumerates down its PCI bus and reaches those
> links. It is also possible the PCIe switch to which the device is attached
> has not been able to train its own links before server enumeration.
>   Is PCIe hotplug built to work on schemes like this? Let us assume that
> the hardware has been designed to trasmit a presence signal once the links
> are trained but this could happen after the server enumeration?

Look at the PCIe hotplug spec, it should answer all of your questions
about this.

>   Incidentally does the server take advantage of the BIOS/UEFI enumeration?

Yes, of course, how else would the kernel be able to enumerate PCI
devices?  :)


greg k-h

Kernelnewbies mailing list

  reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-13 17:40 Sadanand Warrier
2020-02-13 17:48 ` Greg KH [this message]
2020-02-13 19:50   ` Sadanand Warrier

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Kernel Newbies archive on

Archives are clonable:
	git clone --mirror kernelnewbies/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kernelnewbies kernelnewbies/ \
	public-inbox-index kernelnewbies

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone