[libcpu] Add CPU_FEATURE_WRN

The new CPU_FEATURE_WRN macro in the cpu features list will cause the
kernel to emit a warning but not panic if the feature is missing.

src/boot/hardware.cpp

@@ -83,6 +83,7 @@ check_cpu_supported()
     bool supported = true;
 
 #define CPU_FEATURE_OPT(...)
+#define CPU_FEATURE_WRN(...)
 #define CPU_FEATURE_REQ(name, ...) \
     if (!features[cpu::feature::name]) { \
         status::fail(L"CPU required feature " L ## #name, uefi::status::unsupported); \

src/kernel/cpu.cpp

@@ -54,6 +54,10 @@ cpu_validate(cpu_data *c)
 #define CPU_FEATURE_OPT(name, ...) \
     log::verbose(logs::boot, "    Flag %11s: %s", #name, features[cpu::feature::name] ? "yes" : "no");
 
+#define CPU_FEATURE_WRN(name, feat_leaf, feat_sub, regname, bit) \
+    log::verbose(logs::boot, "    Flag %11s: %s", #name, features[cpu::feature::name] ? "yes" : "no"); \
+    if (!features[cpu::feature::name]) log::warn(logs::boot, "Missing cpu feature %s but continuing", #name);
+
 #define CPU_FEATURE_REQ(name, feat_leaf, feat_sub, regname, bit) \
     log::verbose(logs::boot, "    Flag %11s: %s", #name, features[cpu::feature::name] ? "yes" : "no"); \
     kassert(features[cpu::feature::name], "Missing required CPU feature " #name );

src/libraries/cpu/cpu/cpu_id.h

@@ -10,7 +10,9 @@ namespace cpu {
 enum class feature {
 #define CPU_FEATURE_REQ(name, ...)  name,
 #define CPU_FEATURE_OPT(name, ...)  name,
+#define CPU_FEATURE_WRN(name, ...)  name,
 #include "cpu/features.inc"
+#undef CPU_FEATURE_WRN
 #undef CPU_FEATURE_OPT
 #undef CPU_FEATURE_REQ
     max

src/libraries/cpu/cpu/features.inc

@@ -33,6 +33,6 @@ CPU_FEATURE_OPT(rdtscp,     0x80000001, 0, edx, 27)
 CPU_FEATURE_REQ(syscall,    0x80000001, 0, edx, 11)
 CPU_FEATURE_REQ(pdpe1gb,    0x80000001, 0, edx, 26)
 
-CPU_FEATURE_OPT(invtsc,     0x80000007, 0, edx,  8)
+CPU_FEATURE_WRN(invtsc,     0x80000007, 0, edx,  8)
 
 // vim: et

src/libraries/cpu/cpu_id.cpp

@@ -49,12 +49,16 @@ cpu_id::features() const
     if (r.regname & (1ull << bit)) \
         feats.set(feature::name);
 
+#define CPU_FEATURE_WRN(name, feat_leaf, feat_sub, regname, bit) \
+    CPU_FEATURE_OPT(name, feat_leaf, feat_sub, regname, bit);
+
 #define CPU_FEATURE_REQ(name, feat_leaf, feat_sub, regname, bit) \
     CPU_FEATURE_OPT(name, feat_leaf, feat_sub, regname, bit);
 
 #include "cpu/features.inc"
 #undef CPU_FEATURE_OPT
 #undef CPU_FEATURE_REQ
+#undef CPU_FEATURE_WRN
 
     return feats;
 }