From: Jason Gunthorpe <jgg@nvidia.com>
To: Wei Wang <wei.w.wang@hotmail.com>
Cc: bhelgaas@google.com, akpm@linux-foundation.org, bp@alien8.de,
rdunlap@infradead.org, alex@shazbot.org, kevin.tian@intel.com,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH v1] PCI: Add support for ACS Enhanced Capability
Date: Tue, 20 Jan 2026 12:41:12 -0400 [thread overview]
Message-ID: <20260120164112.GD1134360@nvidia.com> (raw)
In-Reply-To: <SI2PR01MB43931A911357962A5E986FFEDC8CA@SI2PR01MB4393.apcprd01.prod.exchangelabs.com>
On Tue, Jan 20, 2026 at 02:11:30AM +0800, Wei Wang wrote:
> Add support for the ACS (Access Control Services) Enhanced Capability,
> introduced with PCIe Gen 5. These new configuration options can be
> controlled via the config_acs= boot parameter.
>
> By default, the ACS Unclaimed Request Redirect Control (URRC) bit is
> enabled if supported by the hardware (i.e., if the ACS Enhanced Capability
> is present). This setting is particularly important for device passthrough
> in virtualization scenarios.
The memory target access bits should be set to request redirect as
well. Linux's grouping logic effectively has assumed the enabled behavior
forever.
Jason
next prev parent reply other threads:[~2026-01-20 16:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-19 18:11 [PATCH v1] PCI: Add support for ACS Enhanced Capability Wei Wang
2026-01-20 16:41 ` Jason Gunthorpe [this message]
2026-01-21 9:18 ` Wei Wang
2026-01-22 15:39 ` Jason Gunthorpe
2026-01-23 1:06 ` Wei Wang
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