Re: [coreboot] printing TSC in printk

[Carl-Daniel Hailfinger]

Any reviews/opinions?

Regards,
Carl-Daniel

On 10.02.2008 00:49, Carl-Daniel Hailfinger wrote:
> On 09.02.2008 21:50, ron minnich wrote:
> > Define a new format letter, T, such that %T as a format means "time".
> >
> > [...] allows us to completely tailor the printing of
> > time, but you have to explicitly add %T when you want time printed.
>
> Preliminary patch[...] does not compile yet, but you get the idea.

Needs an additional declaration in some header to fix compilation, code 
itself should be sound.
> Signed-off-by: Carl-Daniel Hailfinger
> Index: LinuxBIOSv3-printktimestamp/include/console.h
>
> --- LinuxBIOSv3-printktimestamp/include/console.h	(Revision 582)
> +++ LinuxBIOSv3-printktimestamp/include/console.h	(Arbeitskopie)
> @@ -37,6 +37,7 @@
>  unsigned char console_rx_byte(void);
>  int console_tst_byte(void);
>  void die(const char *msg);
> +u32 get_timestamp(void);
>
> struct console_driver {
>    void (*init)(void);
> Index: LinuxBIOSv3-printktimestamp/lib/vtxprintf.c
> ===================================================================
> --- LinuxBIOSv3-printktimestamp/lib/vtxprintf.c	(Revision 582)
> +++ LinuxBIOSv3-printktimestamp/lib/vtxprintf.c	(Arbeitskopie)
> @@ -12,6 +12,7 @@
>  #include <stdarg.h>
>  #include <string.h>
>  #include <div64.h>
> +#include <console.h>
>
> #define isdigit(c)	((c) >= '0' && (c) <= '9')
>  #define is_digit isdigit
> @@ -118,6 +119,7 @@
>    int qualifier;		/* 'h', 'l', or 'L' for integer fields */
>
> int count;
>
> u32 tstamp;
>
> for (count=0; *fmt ; ++fmt) {
> if (*fmt != '%') {
>
> @@ -218,6 +220,16 @@
>    			field_width, precision, flags);
>    		continue;
> /* Timestamp in 32bit hex */
> case 'T':
> 	if (field_width == -1) {
> 		field_width = 2 * sizeof(unsigned long);
> 		flags |= ZEROPAD;
> 	}
> 	tstamp = get_timestamp();
> 	count += number(tx_byte, arg, tstamp, 16,
> 		field_width, precision, flags);
> 	continue;
>
> case 'n':
> 	if (qualifier == 'L') {
> Index: LinuxBIOSv3-printktimestamp/arch/x86/geodelx/cpu.c
>
> --- LinuxBIOSv3-printktimestamp/arch/x86/geodelx/cpu.c	(Revision 582)
> +++ LinuxBIOSv3-printktimestamp/arch/x86/geodelx/cpu.c	(Arbeitskopie)
> @@ -37,6 +37,25 @@
>  /* TODO: Better comment on vsm_end_post_smi, and define 0x05a2 down below. */
>
> /**
> Retrieve a 32-bit time stamp. The generic get_timestamp() offers no guarantee
> whatsoever about monotony, granularity, absence of wraparounds or linear
> relationship between the time stamp and real time.
> This implementation has wraparounds after 2^32 cycles of the TSC register
> and will usually have a linear dependency on real time.
> Qemu and Geode LX support the rdtsc instruction.
> If v3 ever is used on x86 architectures which don't support rdtsc, we have
> to provide an alternative.
> @return 32-bit truncated number of TSC cycles since poweron.
> */
>
> +u32 get_timestamp(void)
> +{
> u32 tstamp;
> __asm__ __volatile__ ("rdtsc" : "=a" (tstamp) : : "edx");
> return tstamp;
>
> +}
>
> +/**
> This is a call to the VSM.
> TODO: We need to know what it does.