On Mon, Apr 01, 2019 at 07:47:14PM -0700, Life is hard, and then you die wrote: > > On Thu, Mar 28, 2019 at 12:29:52PM +0100, Greg Kroah-Hartman wrote: > > On Thu, Mar 28, 2019 at 03:27:55AM -0700, Life is hard, and then you die wrote: > > > > > > On Thu, Mar 28, 2019 at 06:29:17AM +0100, Greg Kroah-Hartman wrote: > > > > On Wed, Mar 27, 2019 at 05:28:17PM -0700, Life is hard, and then you die wrote: > > > > > > > > > > On Wed, Mar 27, 2019 at 11:37:57AM +0900, Greg Kroah-Hartman wrote: > > > > > > On Tue, Mar 26, 2019 at 06:48:06PM -0700, Ronald Tschalär wrote: > > > > > > > This is the dev_xxx() analog to print_hex_dump(), using dev_printk() > > > > > > > instead of straight printk() to match other dev_xxx() logging functions. > > > > > > > --- > > > > > > > drivers/base/core.c | 43 ++++++++++++++++++++++++++++++++++++++++++ > > > > > > > include/linux/device.h | 15 +++++++++++++++ > > > > > > > 2 files changed, 58 insertions(+) > [snip] > > > > > > Anyway, no, please do not do this. Please do not dump large hex values > > > > > > like this to the kernel log, it does not help anyone. > > > > > > > > > > > > You can do this while debugging, sure, but not for "real" kernel code. > > > > > > > > > > As used by this driver, it is definitely called for debugging only and > > > > > must be explicitly enabled via a module param. But having the ability > > > > > for folks to easily generate and print out debugging info has proven > > > > > quite valuable. > > > > > > > > We have dynamic debugging, no need for module parameters at all. This > > > > isn't the 1990's anymore :) > > > > > > I am aware of dynamic debugging, but there are several issues with it > > > from the perspective of the logging I'm doing here (I mentioned these > > > in response to an earlier review already): > > > > > > 1. Dynamic debugging can't be enabled at a function or line level on > > > the kernel command line, so this means that to debug issues > > > during boot you have to enable everything, which can be way too > > > verbose > > > > You can, and should enable it at a function or line level by writing to > > the proper kernel file in debugfs. > > > > You have read Documentation/admin-guide/dynamic-debug-howto.rst, right? > > Yes, and I've played with the parameters quite a bit. > > > No need to do anything on the command line, that's so old-school :) > > Sorry if I'm being unduly dense, but then how to enable debugging > during early boot? The only other alternative I see is modifying the > initrd, and asking folks to do that is noticeably more complicated > than having them add something to the command line in grub. So from my > perspective I find kernel params far from old-school :-) You can do dynamic debugging from the kernel command line, if your code is built into the kernel (but why would a tiny driver under testing like this, not be built into the kernel?) what specifically did not work for you? > > > 2. The expressions to enable the individual logging statements are > > > quite brittle (in particular the line-based ones) since they > > > (may) change any time the code is changed - having stable > > > commands to give to users and put in documentation (e.g. > > > "echo 0x200 > /sys/module/applespi/parameters/debug") is > > > quite valuable. > > > > > > One way to work around this would be to put every single logging > > > statement in a function of its own, thereby ensuring a stable > > > name is associated with each one. > > > > Again, read the documentation, this works today as-is. > > I have read it (we're talking about the dynamic debug docs here), but > I just don't see how it addresses this in any way. You can enable/disable logging per-function, which is what you want, right? Anyway, I'm glad tracepoints work for you, that should be all that is now needed. good luck with your driver! greg k-h
