Date: Tue, 28 May 2019 23:16:27 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Colin Percival <cperciva@freebsd.org>, Warner Losh <imp@bsdimp.com>, Matthew Seaman <matthew@freebsd.org> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Alex Dupre <ale@freebsd.org>, Jonathan Anderson <jonathan@freebsd.org> Subject: Re: Amazon AMIs Message-ID: <2fd62a3f-4490-235f-5aab-e09b21dc14d7@FreeBSD.org> In-Reply-To: <79d5cdad-3a95-de88-25ee-0dd8d27a442e@freebsd.org> References: <f002c020-1e63-c12f-456e-e20f8546a701@FreeBSD.org> <8a139c9c-b98b-4a54-1d7c-0ea1e3dc7a72@freebsd.org> <53a0bd68-a6ba-e8ad-4af2-abeb22e92c03@FreeBSD.org> <E396A0C7-F939-48A1-9B57-D643806B303B@FreeBSD.org> <f51b836f-6a40-9be3-425a-e1afd301507b@FreeBSD.org> <CANCZdfp0ZWe11jXw_xnPi8G2QhyEeBTOcN_ks=sqJCqDjDYcQg@mail.gmail.com> <74ed9ad5-58d9-db02-2e20-b053ba5eeb87@FreeBSD.org> <79d5cdad-3a95-de88-25ee-0dd8d27a442e@freebsd.org>
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On 28/05/2019 21:19, Colin Percival wrote: > On 5/28/19 5:52 AM, Andriy Gapon wrote: >> On 21/02/2019 18:17, Warner Losh wrote: >>> It's hot-unplug that doesn't work quite right. Hotplug works, I believe, if >>> you have PCI_HP in your kernel, I believe. >>> >>> What's needed is about a solid week of cleanup and testing in this area, >>> however. >> >> I am not sure about the context of the latest question... whether it was about >> NVMe hot-plug on real modern hardware or whether it was still about AWS. >> In the latter case, as Colin pointed out earlier[*], PCI_HP would not help at >> all, because the emulated bridge is not a PCIe bridge. >> It seems that they use a mechanism based on an older specification, PCI Standard >> Hot-Plug Controller and Subsystem Specification. > > Right, these EC2 instances look like they have NVMe devices being hotplugged > on a legacy PCI bus attached to an Intel 440FX chipset. There is no real > hardware which behaves the same way as these VMs. I guess so, but I believe that it still conforms to the mentioned specification, at least to a degree (google key words are SHPC+PCI). But I must admit that I haven't actually read it, just skimmed a couple of sections. It looks like Linux has support for that kind of the hot-plug. Just found some additional interesting details: https://github.com/intel/nemu/wiki/ACPI-PCI-discovery-hotplug -- Andriy Gapon
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