On Thu, Apr 6, 2023 at 9:46 AM Rob Landley <r...@landley.net> wrote:
> On 4/5/23 16:30, enh via Toybox wrote: > > I caught someone using pciutils lspci, asked why, and -x (including > > -xxx) and -v (specifically -vvv) were the reasons. I took a quick look, > > and -x in particular seemed easy > > Sigh, -v is gonna be fun. (I think I have some todo notes on it somewhere?) > > Another difference is debian's lspci sorts the output entries, and toybox > is > spitting them out in the order the OS returns them. (Given that "sorting" > is > what I used DIRTREE_BREADTH for last time, I suspect > populate-sort-traverse is a > missing lib/dirtree.c function I need to design. Possibly a new > DIRTREE_SORTED > flag...) > > > (modulo the TODO I've left in the code). > > Specifically: > > + // TODO: where does the "0000:" come from? > + snprintf(toybuf, sizeof(toybuf), > "/sys/bus/pci/devices/0000:%s/config", > > Let's see, linux Documentation/filesystems/sysfs.rst does not contain the > string > "pci", so search for "bus" and > > bus/ contains flat directory layout of the various bus types in the > kernel. Each bus's directory contains two subdirectories:: > > devices/ > drivers/ > > Followed by, I kid you not, "TODO: Finish this section." When was that... > > 929f6378df7d0 (Patrick Mochel 2003-01-10 04:45:58 -0600 332)TODO: > Finish > this section. > > Just over twenty years ago. Well of course. (Remember how I said the > linux-kernel development community has been contracting as it continually > raises > the barrier not just to entry but to continued participation? Yeah, that.) > > Ok, switching over to looking at the source code, find . -name pci, > drivers/pci > looks likely, grep '"bus' * finds proc.c, and grep '[:]' proc.c to see who > is > printing out a colon finds: > > sprintf(name, "%04x:%02x", pci_domain_nr(bus), > bus->number); > > on line 416, and THAT is in include/linux/pci.h where it's always 0 unless > you've enabled CONFIG_PCI_DOMAINS, and THAT config symbol lives in > drivers/pci/Kconfig where it DOES NOT HAVE ANY HELP TEXT. Because of > course not. > > Here's the patch that added it, which ALSO doesn't say what it is: > > https://lwn.net/Articles/35497/ > > Right, Jonathan Corbet wrote a book, which explains what Linux thinks PCI > Domains are: > > > https://www.oreilly.com/library/view/linux-device-drivers/0596005903/ch12.html#:~:text=domains > > Apparently they came up with their own name for PCI segments for some > reason, > and despite claiming that "modern workstations" now have two of them, the > book > does not actually have an example with a domain number other than zero. > > > I notice that half the pci devices on my machine are missing from the > > toybox lspci output versus the pciutils lspci --- it looks like > > scan_uevent() is returning 2 for the bridges? > > The downside of doing this kind of plumbing is the need for test hardware > to try > it on to experience the full range of weird crap different drivers are > emitting. :( > > If scan_uevent returning 2 means the relevant uevent file had only two of > "DRIVER=", "PCI_CLASS=%x" and "PCI_ID=%x:%x", which I'm not seeing here? > > $ egrep -Hc '(DRIVER|PCI_CLASS|PCI_ID)=' /sys/bus/pci/devices/*/uevent > /sys/bus/pci/devices/0000:00:00.0/uevent:3 > /sys/bus/pci/devices/0000:00:02.0/uevent:3 > /sys/bus/pci/devices/0000:00:14.0/uevent:3 > /sys/bus/pci/devices/0000:00:16.0/uevent:3 > /sys/bus/pci/devices/0000:00:19.0/uevent:3 > /sys/bus/pci/devices/0000:00:1a.0/uevent:3 > /sys/bus/pci/devices/0000:00:1b.0/uevent:3 > /sys/bus/pci/devices/0000:00:1c.0/uevent:3 > /sys/bus/pci/devices/0000:00:1c.1/uevent:3 > /sys/bus/pci/devices/0000:00:1c.2/uevent:3 > /sys/bus/pci/devices/0000:00:1c.3/uevent:3 > /sys/bus/pci/devices/0000:00:1c.5/uevent:3 > /sys/bus/pci/devices/0000:00:1d.0/uevent:3 > /sys/bus/pci/devices/0000:00:1f.0/uevent:3 > /sys/bus/pci/devices/0000:00:1f.2/uevent:3 > /sys/bus/pci/devices/0000:00:1f.3/uevent:3 > /sys/bus/pci/devices/0000:02:00.0/uevent:3 > /sys/bus/pci/devices/0000:0b:00.0/uevent:3 > yeah, sorry, i hadn't had time to look any further to see _what_ was missing. changing one character in your grep is easy though... ...looks like pci bridges don't have a driver? $ egrep -H '(DRIVER|PCI_CLASS|PCI_ID)=' /sys/bus/pci/devices/*/uevent /sys/bus/pci/devices/0000:00:00.0/uevent:PCI_CLASS=60000 /sys/bus/pci/devices/0000:00:00.0/uevent:PCI_ID=8086:1237 /sys/bus/pci/devices/0000:00:01.0/uevent:PCI_CLASS=60100 /sys/bus/pci/devices/0000:00:01.0/uevent:PCI_ID=8086:7110 /sys/bus/pci/devices/0000:00:01.3/uevent:PCI_CLASS=68000 /sys/bus/pci/devices/0000:00:01.3/uevent:PCI_ID=8086:7113 /sys/bus/pci/devices/0000:00:03.0/uevent:DRIVER=virtio-pci /sys/bus/pci/devices/0000:00:03.0/uevent:PCI_CLASS=0000 /sys/bus/pci/devices/0000:00:03.0/uevent:PCI_ID=1AF4:1004 /sys/bus/pci/devices/0000:00:04.0/uevent:DRIVER=virtio-pci /sys/bus/pci/devices/0000:00:04.0/uevent:PCI_CLASS=20000 /sys/bus/pci/devices/0000:00:04.0/uevent:PCI_ID=1AF4:1000 /sys/bus/pci/devices/0000:00:05.0/uevent:DRIVER=virtio-pci /sys/bus/pci/devices/0000:00:05.0/uevent:PCI_CLASS=FF00 /sys/bus/pci/devices/0000:00:05.0/uevent:PCI_ID=1AF4:1005 $ > Rob >
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