From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate001.proxmox.com (gate001.proxmox.com [45.144.208.40]) by lore.proxmox.com (Postfix) with ESMTPS id E58431FF0E5 for ; Wed, 29 Jul 2026 12:25:30 +0200 (CEST) Received: from gate001.proxmox.com (localhost.localdomain [127.0.0.1]) by gate001.proxmox.com (Proxmox) with ESMTP id 9023221330; Wed, 29 Jul 2026 12:25:30 +0200 (CEST) Message-ID: <78a32cca-3e53-4418-82cf-7fabf83d8c32@proxmox.com> Date: Wed, 29 Jul 2026 12:25:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: qm showcmd shows incorrect PCI device address To: pve-devel@lists.proxmox.com References: <2821634225-1232228@mx.rootnet.nl> Content-Language: en-US From: Fiona Ebner In-Reply-To: <2821634225-1232228@mx.rootnet.nl> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1785320670022 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.170 Adjusted score from AWL reputation of From: address DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment (newer systems) RCVD_IN_DNSWL_LOW -0.7 Sender listed at https://www.dnswl.org/, low trust SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Message-ID-Hash: GIIN7RMGYBVQ3D36OUUHSEADUMJK577E X-Message-ID-Hash: GIIN7RMGYBVQ3D36OUUHSEADUMJK577E X-MailFrom: f.ebner@proxmox.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: niels@rootnet.nl X-Mailman-Version: 3.3.10 Precedence: list List-Id: Proxmox VE development discussion List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Just for the record, this was already answered in the forum: https://forum.proxmox.com/threads/qm-showcmd-shows-incorrect-pci-device-address.185370/ And a bugzilla issue was opened afterwards: https://bugzilla.proxmox.com/show_bug.cgi?id=7857 Best Regards, Fiona Am 28.07.26 um 3:07 PM schrieb Niels Hendriks: > Hello, > > > As is probably known, there are quite a few issues with reliable PCI passthrough. > We've been able to get PCI passthrough working well, with one caveat: if GPU 1 is assigned to VM A, and is then re-assigned to VM B, it sometimes does not come up properly. The error we get within the VM is that the GPU has "fallen off the bus". > We have tried many things, but the only way to reliably resolve this is to run a pre-start hookscript that removes the PCI device and re-discovers it. > > > We use a resource mapping to simplify the VM configs, and to determine which device has to be removed and re-discovered, we use the "qm showcmd " command. > However, we found out this does not work reliably. the showcmd command actually always appears to show the first PCI address of the resource mapping. And if >1 GPU is present it would show the first addresses of the GPU resource mapping. > > > This appears to be caused by this change: https://www.mail-archive.com/pve-devel@lists.proxmox.com/msg27318.html > > > This appears to be an intended change, but I don't know if my usecase was considered when the change was made. > Is there a different way to determine the PCI address(es) that will be used when starting a VM using a resource mapping? Or is this actually an unintended side-effect? > > > Alternatively we could remove the resource mapping of course, but if possible we would like to avoid doing that (for a simpler VM configuration) > > > Thank you > Niels Hendriks > > __________________________________________________________ > RootNet B.V. > > Helpdesk: 024 3500112 (9:00 - 17:30) > Service meldingen: rootnet.network