On Tuesday 06 October 2020 17:22:22 Bjorn Helgaas wrote: > It's not obvious from the code why we need pci_sysfs_init(), but > Yinghai hinted [1] that we need to create sysfs after assigning > resources. I experimented by removing pci_sysfs_init() and skipping > the ROM BAR sizing. In that case, we create sysfs files in > pci_bus_add_device() and later assign space for the ROM BAR, so we > fail to create the "rom" sysfs file. > > The current solution to that is to delay the sysfs files until > pci_sysfs_init(), a late_initcall(), which runs after resource > assignments. But I think it would be better if we could create the > sysfs file when we assign the BAR. Then we could get rid of the > late_initcall() and that implicit ordering requirement. > > But I haven't tried to code it up, so it's probably more complicated > than this. I guess ideally we would assign all the resources before > pci_bus_add_device(). If we could do that, we could just remove > pci_sysfs_init() and everything would just work, but I think that's a > HUGE can of worms. > > [1] https://lore.kernel.org/linux-pci/CAE9FiQWBXHgz-gWCmpWLaBOfQQJwtRZemV6Ut9GVw_KJ-dTGTA@xxxxxxxxxxxxxx/ I found out that pci_sysfs_init() function was introduced in kernel version 2.6.10 by this historic commit: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=f6d553444da20cd1e44f2c4864c2d0c56c934e0a So it was really due to PCI ROM BAR and accessing it from sysfs.
