-----Original Message----- From: Pierre-Louis Bossart [mailto:pierre-louis.bossart@linux.intel.com] Sent: Wednesday, May 2, 2018 9:20 PM
The kernel debug message from SOF driver can help us to debug issues and
CI to provide hints for failed test cases. But it will be too much to output all of debug message by default.
So maybe we can try to manage SOF debug messages as drm does?
DRM is kernel gfx subsystem and Intel i915 driver is based on it. drm
defines a module parameter 'debug' for user to specify a debug mask when booting the kernel. The debug mask is a bit mask of different message categories. By setting a suitable mask, user or CI can make DRM driver output message of specified categories. Usually we use drm.debug=0x0e to get most important debug messages.
Maybe SOF driver can use this method to configure its messages? If this is
doable, we can do some RFC patch.
Here is how drm defines its debug mode in drivers/gpu/drm/drm_drv.c:
MODULE_PARM_DESC(debug, "Enable debug output, where each bit
enables a debug category.\n"
"\t\tBit 0 (0x01) will enable CORE messages (drm core code)\n" "\t\tBit 1 (0x02) will enable DRIVER messages (drm controller code)\n" "\t\tBit 2 (0x04) will enable KMS messages (modesetting code)\n" "\t\tBit 3 (0x08) will enable PRIME messages (prime code)\n" "\t\tBit 4 (0x10) will enable ATOMIC messages (atomic code)\n" "\t\tBit 5 (0x20) will enable VBL messages (vblank code)\n" "\t\tBit 7 (0x80) will enable LEASE messages (leasing code)");
not a bad idea for developers. when folks debug topology or IPC stuff, they don't necessarily care about PCM or page tables, so it's a good
way to filter.
we could have one bit per module (core, pcm, ipc, topology, acpi, pci, etc).
I don't see how this improves CI work though?
CI can save the debug message for developers to debug failed test cases.
And 0day can also detect some pattern in the debug message to decide if there is an audio test case failure.
ok, but you will have to find a debug level that is both verbose enough to point to the problem without overwhelming the reader...
However, 0day does not allow us to apply patch enable DEBUG by default
in Makefile. That's why I want to introduce a kernel module parameter to control this at runtime.
I'll check how ALSA uses snd_debug() or snd_printk() as Liam suggested.
Maybe we can build sof_debug on top of them.
if we want this to be used in other OSes we might as well create a log mechanism which can be easily ported without dependencies on GPL or alsa.
Thanks for the tips. I overlooked this.
ALSA and ASoC use dev_warn() and dev_err() to output warning and errors. ALSA also defines snd_printk() based on printk(). But ALSA and ASoC core don't use snd_printk() themselves, they just output warning and errors.
DRM implements its drm_dev_printk() based on dev_printk().
So for SOF log mechanism, it seems we don't need to use snd_printk(). We may introduce an adaption layer. On Linux, it can be based on dev_printk(const char *level, const struct device *dev, const char *fmt, ...). For other non-GPL OSes, we can change the implementation.
Thanks Mengdong
Thanks Mengdong
module_param_named(debug, drm_debug, int, 0600);
void drm_dev_printk(const struct device *dev, const char *level, unsigned int category, const char *function_name, const char *prefix, const char *format, ...) { struct va_format vaf; va_list args;
if (category != DRM_UT_NONE && !(drm_debug & category)) return;
va_start(args, format); vaf.fmt = format; vaf.va = &args;
if (dev) dev_printk(level, dev, DRM_PRINTK_FMT, function_name,
prefix,
&vaf);... }
Then base on this, it defines macros for outputting of different
categories:
#define DRM_DEV_DEBUG(dev, fmt, args...)
\
drm_dev_printk(dev, KERN_DEBUG, DRM_UT_CORE, __func__, "",
fmt, \
##args)#define DRM_DEBUG(fmt, ...)
\
drm_printk(KERN_DEBUG, DRM_UT_CORE, fmt, ##__VA_ARGS__)
#define DRM_DEV_DEBUG_DRIVER(dev, fmt, args...)
\
drm_dev_printk(dev, KERN_DEBUG, DRM_UT_DRIVER, __func__, "",
\
fmt, ##args)#define DRM_DEBUG_DRIVER(fmt, ...)
\
drm_printk(KERN_DEBUG, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
#define DRM_DEV_DEBUG_KMS(dev, fmt, args...)
\
drm_dev_printk(dev, KERN_DEBUG, DRM_UT_KMS, __func__, "", fmt,
\
##args)Thanks Mengdong
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