[+cc folks from related discussion at https://lore.kernel.org/r/20241213202942.44585-1-tdave@xxxxxxxxxx] On Sun, Sep 15, 2024 at 10:36:58AM +0900, Akihiko Odaki wrote: > The documentation used to say: > > For example, > > pci=config_acs=10x > > would configure all devices that support ACS to enable P2P Request > > Redirect, disable Translation Blocking, and leave Source Validation > > unchanged from whatever power-up or firmware set it to. > > However, a flag specification always needs to be suffixed with "@" and a > PCI device string, which is missing in this example. It needs to be > suffixed with "@pci:0:0" to configure all devices that support ACS in > particular. Thanks for the patch. Krzysztof added a bit to the commit log at: https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?id=57722057d762 but I think we should also include the flags template: config_acs = Format: <ACS flags>@<pci_dev>[; ...] so the commit log includes a hint about what "flag specification" means. Also, I think the "pci_dev" documentation is poor and should be improved in a second patch. The only current mention I see is here: pci=option[,option...] [PCI,EARLY] various PCI subsystem options. Some options herein operate on a specific device or a set of devices (<pci_dev>). These are specified in one of the following formats: [<domain>:]<bus>:<dev>.<func>[/<dev>.<func>]* pci:<vendor>:<device>[:<subvendor>:<subdevice>] Note: the first format specifies a PCI bus/device/function address which may change if new hardware is inserted, if motherboard firmware changes, or due to changes caused by other kernel parameters. If the domain is left unspecified, it is taken to be zero. Optionally, a path to a device through multiple device/function addresses can be specified after the base address (this is more robust against renumbering issues). The second format selects devices using IDs from the configuration space which may match multiple devices in the system. where I guess "pci_dev" means the second format: pci:<vendor>:<device>[:<subvendor>:<subdevice>] and apparently "pci:0:0" means all devices with vendor==0 and device==0, and it's not completely obvious to me that this means "all devices". > --- > Documentation/admin-guide/kernel-parameters.txt | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index ee2984e46c06..5611903c27a9 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -4604,7 +4604,7 @@ > '1' – force enabled > 'x' – unchanged > For example, > - pci=config_acs=10x > + pci=config_acs=10x@pci:0:0 > would configure all devices that support > ACS to enable P2P Request Redirect, disable > Translation Blocking, and leave Source > > --- > base-commit: 46a0057a5853cbdb58211c19e89ba7777dc6fd50 > change-id: 20240911-acs-3043a2737cc9 > > Best regards, > -- > Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> >
