[RFC] libata debugging

On Wednesday 24 August 2005 23:04, Borislav Petkov wrote:
Hi there,

Jeff asked for a volunteer a couple days ago on lkml to implement libata 
debugging similar to the netdev debugging (see thread "Another libata TODO 
item") and I decided to give it a try. Here's a forward message I sent to him 
with the loglevels I think should be there and some additional implementation 
details I think should be discussed first before any coding attempts. Any 
comments are greatly appreciated.

Regards,
Boris.

Hi Jeff,

after going through libata-core and libata-scsi.c here are the logging
levels I think might be appropriate:

ATA_MSG_DRV		0x0001
ATA_MSG_INFO	0x0002
ATA_MSG_PROBE 	0x0004
ATA_MSG_WARN 	0x0008
ATA_MSG_MALLOC	0x0010
ATA_MSG_CTL 		0x0020
ATA_MSG_INTR	0x0040
ATA_MSG_ERR		0x0080


ATA_MSG_DRV:
Driver info messages such as identity, version and copyright info.

ATA_MSG_INFO:
a little more verbose device config messages (to replace all printk's with
KERN_INFO loglevel)

ATA_MSG_PROBE:
interaction with the controller. (printing of (un-)supported features while
configuring the device; features setting as in ata_dev_set_xfermode() for
example)

ATA_MSG_WARN:
warning messages like
printk(KERN_WARNING "ata%u: no PIO support\n", ap->id);
for example.

ATA_MSG_MALLOC:
debugging allocation, deallocation and mapping of driver memory.

ATA_MSG_CTL:
highly verbose device control/hardware registers (for ex. 
ata_dev_select()), resetting the controller, etc. To replace mostly the
debugging DPRINTK's.

ATA_MSG_INTR:
interrupt handling

ATA_MSG_ERR:
fatal hardware and other errors


It seems to me though that these debug levels do not have the level of
granularity that libata should probably have, although I don't see more
subgroupings besides maybe an additional loglevel strictly for SCSI/ATA
commands sent to the controller.

Should we also replace all those enter/exit debug statements -
VPRINTK("ENTER\n"); - with something like
VPRINTK("function_name():ENTER\n"); for more easly locating the place in
the code that the problem happens while debugging.

Should the userspace setting of debug levels be done maybe through /proc
like the ide cdrom driver, for example: /proc/sys/dev/cdrom/debug, so
writing the ATA_MSG_XXX unsigned value there would enable or disable
debugging?

I know that in open source you just do things but i still think it is
better to run these by you first and then do the patches. :)

Regards,
Boris.