hi : 2011/2/7 Greg KH <greg@xxxxxxxxx>: > On Sun, Feb 06, 2011 at 05:23:01PM +0800, loody wrote: >> hi: >> >> 2011/2/6 loody <miloody@xxxxxxxxx>: >> > hi all: >> > I want to use snprintf for collecting debug message and print it later. >> > But I found : >> > 1. when I add "\n" as below, the buffer will be cleared, that means >> > the "irq status" will put at the head of Buffer instead of at the end >> > of "ehci work". >> > Size -= snprintf (Buffer , Size,"ehci_work\n"); >> > Size -= snprintf (Buffer , Size,"irq status 0x%x\n",status); >> > is it possible to add "\n" in the buffer, but will will not reset the buffer? >> > >> > 2. instead of snprintf, is there any better idea for saving debug >> > message and show it out later? >> 3. is there any function in kernel, like snprintf, which will also >> collect strings but tread the buffer as ring buffer, such that I will >> not need to take care the overflow. > > Look at include/linux/ring_buffer.h I found some code such as ftrace seems use ring_buffer to record the data. but the source is hard to understand for me right now. :-) Is there simple sample code or document for me to reference? -- Thank U, miloody _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
