diff mbox series

[v9,2/6] Documentation/kernel-parameters: Add multi-device config_acs example

Message ID SI2PR01MB439342D6BDCFD10A2B6207B9DCB62@SI2PR01MB4393.apcprd01.prod.exchangelabs.com
State New
Headers show
Series PCI: Add support for ACS Enhanced Capability | expand

Commit Message

Wei Wang Sept. 3, 2026, 3:46 a.m. UTC 
The config_acs parameter allows configuring ACS settings for multiple PCI
devices by separating entries with semicolons. The current documentation
only illustrates applying one configuration pattern to all devices, but
does not show how to specify multiple devices with different ACS settings
in a single parameter. Add an example demonstrating multi-device usage
with distinct ACS configurations.

Some bootloaders interpret ';' as a command separator, which can cause
the parameter to be split as multiple commands. Document that the entire
parameter may need to be quoted to avoid bootloader parsing issues. This
avoids confusing bootloader errors such as "can't find command <BDF>"
when passing multiple device entries.

Signed-off-by: Wei Wang <wei.w.wang@hotmail.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

sashiko-bot@kernel.org Sept. 3, 2026, 4:06 a.m. UTC | #1 
> The config_acs parameter allows configuring ACS settings for multiple PCI
> devices by separating entries with semicolons. The current documentation
> only illustrates applying one configuration pattern to all devices, but
> does not show how to specify multiple devices with different ACS settings
> in a single parameter. Add an example demonstrating multi-device usage
> with distinct ACS configurations.
> 
> Some bootloaders interpret ';' as a command separator, which can cause
> the parameter to be split as multiple commands. Document that the entire
> parameter may need to be quoted to avoid bootloader parsing issues. This
> avoids confusing bootloader errors such as "can't find command <BDF>"
> when passing multiple device entries.
> 
> Signed-off-by: Wei Wang <wei.w.wang@hotmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!
diff mbox series

Patch

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 63f0c66c9123..a2563ff69f51 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5345,6 +5345,13 @@  Kernel parameters
 
 				Note: this may remove isolation between devices
 				and may put more devices in an IOMMU group.
+
+				  "pci=config_acs=10x@0000:04:00.0;1x101@0000:84:00.0"
+				configures two devices with different ACS settings.
+				Note: Some bootloaders interpret ';' as a command
+				separator. If so, quote the entire parameter to
+				ensure it is passed to the kernel unchanged.
+
 		force_floating	[S390] Force usage of floating interrupts.
 		nomio		[S390] Do not use MIO instructions.
 		norid		[S390] ignore the RID field and force use of