Hi Ingo, On 03/16/2017 03:17 PM, Ingo Molnar wrote: > * Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote: > >> Hi Ingo, >> >> On 03/02/2017 02:40 PM, Ingo Molnar wrote: >>> * Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote: >>> >>>> Hi Ingo, >>>> >>>> How about this version? Any further comments? >>> So I have re-read the review feedback I gave on Jan 19 and found at least one >>> thing I pointed out that you didn't address in the latest patches ... >> Do you mind telling me which one is not addressed? Is it one of below >> feedbacks? > So one piece of feedback I gave was: > > | BTW., just a side note, some kernel developers (like PeterZ - and I do it > | sometimes too) remap early_printk to printk permanently and use it as their main > | printk facility - because printk() reliability has suffered over the last couple > | of years. > | > | So it's more than just early boot debugging - it's a very simple state-less > | logging facility to an external computer. > > But the latest Kconfig help text still says this: > > +config EARLY_PRINTK_USB_XDBC > + bool "Early printk via the xHCI debug port" > + depends on EARLY_PRINTK && PCI > + select EARLY_PRINTK_USB > + ---help--- > + Write kernel log output directly into the xHCI debug port. > + > + This is useful for kernel debugging when your machine crashes very > + early before the console code is initialized. For normal operation > + it is not recommended because it looks ugly and doesn't cooperate > + with klogd/syslogd or the X server. You should normally N here, > + unless you want to debug such a crash. > > ... while in reality it's an alternative lockless logging facility that goes way > beyond debugging early boot crashes! > > Granted, I qualified that with 'just a side note'. I guess something like this > would work: > > + One use for this feature is kernel debugging, for example when your > + machine crashes very early before the regular console code is > + initialized. Other uses include simpler, lockless logging instead of a > + full-blown printk console driver + klogd. > + > + For normal production environments this is normally not recommended, > + because it doesn't feed events into klogd/syslogd and doesn't try to > + print anything on the screen. > + > + You should normally N here, unless you want to debug early crashes or > + need a very simple printk logging facility. Very appreciated for pointing this out. I will replace it. > > Another piece of feedback I gave was: > >>> +config USB_EARLY_PRINTK >>> + bool >> Also, could we standardize the nomencalture to not be a mixture of prefixes and >> postfixes - i.e. standardize on postfixes (as commonly done in the Kconfig >> space) and rename this one to EARLY_PRINTK_USB or so? > yet your latest submission still includes the very same postfixed config switch > name that collides with the prefixed names such as EARLY_PRINTK_USB: > > --- a/drivers/usb/Kconfig > +++ b/drivers/usb/Kconfig > @@ -19,6 +19,9 @@ config USB_EHCI_BIG_ENDIAN_MMIO > config USB_EHCI_BIG_ENDIAN_DESC > bool > > +config USB_EARLY_PRINTK > + bool > + > menuconfig USB_SUPPORT > bool "USB support" > depends on HAS_IOMEM > > The problem I tried to point out with my review feedback is that we thus have > both: > > CONFIG_EARLY_PRINTK_USB=y > CONFIG_USB_EARLY_PRINTK=y > > ... which is confusing at the very least. > > On a second look, this config switch appears to be unused - is it a leftover from > earlier patches? Yes, it is a leftover from the earlier patches. I should remove it. Sorry about it. > > The patches don't look too bad otherwise, so we are not far from having something > acceptable, IMHO. > Thanks. For the typo and grammar issues, I will recheck the patches and ask some English speakers for review. Best regards, Lu Baolu -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
