On 09.02.2026 11:31, Teddy Astie wrote:
> @@ -93,6 +96,7 @@ void show_help(void)
> " units default to
> \"us\" if unspecified.\n"
> " truncates
> un-representable values.\n"
> " 0 lets the hardware
> decide.\n"
> + " get-intel-temp [cpuid] get Intel CPU temperature
> of <cpuid> or all\n"
Sorry, thinking about it only now: Do we really want to build in the vendor
name to a command? "get-temp" would allow for adding an AMD implementation
later on?
> @@ -1354,6 +1358,131 @@ void enable_turbo_mode(int argc, char *argv[])
> errno, strerror(errno));
> }
>
> +static int fetch_dts_temp(xc_interface *xch, uint32_t cpu, bool package, int
> *temp)
> +{
> + xc_resource_entry_t entries[] = {
> + { .idx = package ? MSR_PACKAGE_THERM_STATUS : MSR_IA32_THERM_STATUS
> },
> + { .idx = MSR_TEMPERATURE_TARGET },
> + };
> + struct xc_resource_op ops = {
> + .cpu = cpu,
> + .entries = entries,
> + .nr_entries = ARRAY_SIZE(entries),
> + };
> + int tjmax;
> +
> + int ret = xc_resource_op(xch, 1, &ops);
> +
> + switch ( ret )
> + {
> + case -1:
> + /* xc_resource_op returns -1 in out of memory scenarios */
> + errno = -ENOMEM;
And xc_resource_op() doesn't itself set / inherit a properly set errno?
We don't want to override what the C library may have set.
> + return -1;
> +
> + case 0:
> + /* This CPU isn't online or can't query this MSR */
> + errno = -ENODATA;
> + return -1;
Here we "synthesize" an error, so errno indeed needs setting. However,
doesn't errno want setting to positive E... values?
> + case 1:
> + {
> + /*
> + * The CPU doesn't support MSR_TEMPERATURE_TARGET, we assume it's 100
> + * which is correct aside a few selected Atom CPUs. Check Linux
> + * kernel's coretemp.c for more information.
> + */
> + static bool has_reported_once = false;
> +
> + if ( !has_reported_once )
> + {
> + fprintf(stderr, "MSR_TEMPERATURE_TARGET is not supported, assume
> "
> + "tjmax = 100, readings may be incorrect.\n");
> + has_reported_once = true;
> + }
> +
> + tjmax = 100;
> + break;
> + }
> +
> + case 2:
> + tjmax = (entries[1].val >> 16) & 0xff;
> + break;
> +
> + default:
> + if ( ret > 0 )
> + {
> + fprintf(stderr, "Got unexpected xc_resource_op return value:
> %d", ret);
> + errno = -EINVAL;
> + }
> + else
> + errno = ret;
Why would this be? How do you know "ret" holds a value suitable for putting
in errno?
Jan
