Messages in this thread | | | Date | Fri, 10 Aug 2018 11:35:01 +0200 | From | Martin Mares <> | Subject | Re: lspci: Display path to device |
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Hello!
> I don't like telling the user to grovel around lspci -t by hand. It's > not many lines of code to add a new -P option to lspci to show the path > to each device instead of bus:dev.fn
I like the feature, but I have a couple of minor objections to the implementation:
> -static char options[] = "nvbxs:d:ti:mgp:qkMDQ" GENERIC_OPTIONS ; > +static char options[] = "nvbxs:d:tPi:mgp:qkMDQ" GENERIC_OPTIONS ;
Please update the help_msg, too.
> +static void > +show_slot_path(struct pci_dev *p) > +{ > + struct pci_dev *d = NULL; > + > + if (opt_path && p->bus) > + { > + for (d = p->access->devices; d; d = d->next) { > + if (d->hdrtype == -1) > + d->hdrtype = pci_read_byte(d, PCI_HEADER_TYPE) & 0x7f;
Please do not modify the hdrtype field, it is private to libpci.
Instead, always read the PCI_HEADER_TYPE register. It will be fast since lspci caches configuration space accesses.
> + if (d->hdrtype != PCI_HEADER_TYPE_BRIDGE && > + d->hdrtype != PCI_HEADER_TYPE_CARDBUS) > + continue; > + if (pci_read_byte(d, PCI_SECONDARY_BUS) > p->bus) > + continue; > + if (pci_read_byte(d, PCI_SUBORDINATE_BUS) < p->bus) > + continue;
Beware, cardbus bridges use different registers for secondary and subordinate bus.
... the more I think about it, the more I am convinced that we want to re-use the bus topology builder from ls-tree.c. I will give it a try, stay tuned.
Martin
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