@@ -866,6 +866,16 @@
dscc4.setup= [NET]
+ dt_cpu_ftrs= [PPC]
+ Format: {"off" | "known"}
+ Control how the dt_cpu_ftrs device-tree binding is
+ used for CPU feature discovery and setup (if it
+ exists).
+ off: Do not use it, fall back to legacy cpu table.
+ known: Do not pass through unknown features to guests
+ or userspace, only those that the kernel is not aware
+ of.
+
dump_apple_properties [X86]
Dump name and content of EFI device properties on
x86 Macs. Useful for driver authors to determine
@@ -391,11 +391,6 @@ config PPC_DT_CPU_FTRS
firmware provides this binding.
If you're not sure say Y.
-config PPC_CPUFEATURES_ENABLE_UNKNOWN
- bool "cpufeatures pass through unknown features to guest/userspace"
- depends on PPC_DT_CPU_FTRS
- default y
-
config HIGHMEM
bool "High memory support"
depends on PPC32
@@ -8,6 +8,7 @@
#include <linux/export.h>
#include <linux/init.h>
#include <linux/jump_label.h>
+#include <linux/libfdt.h>
#include <linux/memblock.h>
#include <linux/printk.h>
#include <linux/sched.h>
@@ -670,12 +671,24 @@ static struct dt_cpu_feature_match __initdata
{"wait-v3", feat_enable, 0},
};
-/* XXX: how to configure this? Default + boot time? */
-#ifdef CONFIG_PPC_CPUFEATURES_ENABLE_UNKNOWN
-#define CPU_FEATURE_ENABLE_UNKNOWN 1
-#else
-#define CPU_FEATURE_ENABLE_UNKNOWN 0
-#endif
+static bool __initdata using_dt_cpu_ftrs;
+static bool __initdata enable_unknown = true;
+
+static int __init dt_cpu_ftrs_parse(char *str)
+{
+ if (!str)
+ return 0;
+
+ if (!strcmp(str, "off"))
+ using_dt_cpu_ftrs = false;
+ else if (!strcmp(str, "known"))
+ enable_unknown = false;
+ else
+ return 1;
+
+ return 0;
+}
+early_param("dt_cpu_ftrs", dt_cpu_ftrs_parse);
static void __init cpufeatures_setup_start(u32 isa)
{
@@ -706,7 +719,7 @@ static bool __init cpufeatures_process_feature(struct dt_cpu_feature *f)
}
}
- if (!known && CPU_FEATURE_ENABLE_UNKNOWN) {
+ if (!known && enable_unknown) {
if (!feat_try_enable_unknown(f)) {
pr_info("not enabling: %s (unknown and unsupported by kernel)\n",
f->name);
@@ -755,6 +768,26 @@ static void __init cpufeatures_setup_finished(void)
cur_cpu_spec->cpu_features, cur_cpu_spec->mmu_features);
}
+static int __init disabled_on_cmdline(void)
+{
+ unsigned long root, chosen;
+ const char *p;
+
+ root = of_get_flat_dt_root();
+ chosen = of_get_flat_dt_subnode_by_name(root, "chosen");
+ if (chosen == -FDT_ERR_NOTFOUND)
+ return false;
+
+ p = of_get_flat_dt_prop(chosen, "bootargs", NULL);
+ if (!p)
+ return false;
+
+ if (strstr(p, "dt_cpu_ftrs=off"))
+ return true;
+
+ return false;
+}
+
static int __init fdt_find_cpu_features(unsigned long node, const char *uname,
int depth, void *data)
{
@@ -765,8 +798,6 @@ static int __init fdt_find_cpu_features(unsigned long node, const char *uname,
return 0;
}
-static bool __initdata using_dt_cpu_ftrs = false;
-
bool __init dt_cpu_ftrs_in_use(void)
{
return using_dt_cpu_ftrs;
@@ -774,6 +805,8 @@ bool __init dt_cpu_ftrs_in_use(void)
bool __init dt_cpu_ftrs_init(void *fdt)
{
+ using_dt_cpu_ftrs = false;
+
/* Setup and verify the FDT, if it fails we just bail */
if (!early_init_dt_verify(fdt))
return false;
@@ -781,6 +814,9 @@ bool __init dt_cpu_ftrs_init(void *fdt)
if (!of_scan_flat_dt(fdt_find_cpu_features, NULL))
return false;
+ if (disabled_on_cmdline())
+ return false;
+
cpufeatures_setup_cpu();
using_dt_cpu_ftrs = true;
@@ -1026,5 +1062,8 @@ static int __init dt_cpu_ftrs_scan_callback(unsigned long node, const char
void __init dt_cpu_ftrs_scan(void)
{
+ if (!using_dt_cpu_ftrs)
+ return;
+
of_scan_flat_dt(dt_cpu_ftrs_scan_callback, NULL);
}