Reviewers: Mads Ager,
Description:
Improve V8 VFPv3 runtime detection, to address issue 914.
This patch will check for the exact word vfpv3 as well as 0xc08 (CortexA8
part number) as some earlier kernel didn't report vfpv3 for A8.
Please review this at http://codereview.chromium.org/4103013/show
SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/
Affected files:
M src/platform-linux.cc
Index: src/platform-linux.cc
===================================================================
--- src/platform-linux.cc (revision 5749)
+++ src/platform-linux.cc (working copy)
@@ -99,30 +99,12 @@
#ifdef __arm__
-bool OS::ArmCpuHasFeature(CpuFeature feature) {
- const char* search_string = NULL;
+static bool CPUInfoContainsString(const char * search_string) {
const char* file_name = "/proc/cpuinfo";
- // Simple detection of VFP at runtime for Linux.
- // It is based on /proc/cpuinfo, which reveals hardware configuration
- // to user-space applications. According to ARM (mid 2009), no similar
- // facility is universally available on the ARM architectures,
- // so it's up to individual OSes to provide such.
- //
// This is written as a straight shot one pass parser
// and not using STL string and ifstream because,
// on Linux, it's reading from a (non-mmap-able)
// character special device.
- switch (feature) {
- case VFP3:
- search_string = "vfp";
- break;
- case ARMv7:
- search_string = "ARMv7";
- break;
- default:
- UNREACHABLE();
- }
-
FILE* f = NULL;
const char* what = search_string;
@@ -149,6 +131,43 @@
// Did not find string in the proc file.
return false;
}
+
+bool OS::ArmCpuHasFeature(CpuFeature feature) {
+ const int max_items = 2;
+ const char* search_strings[max_items] = { NULL, NULL };
+ int search_items = 0;
+ // Simple detection of VFP at runtime for Linux.
+ // It is based on /proc/cpuinfo, which reveals hardware configuration
+ // to user-space applications. According to ARM (mid 2009), no similar
+ // facility is universally available on the ARM architectures,
+ // so it's up to individual OSes to provide such.
+ switch (feature) {
+ case VFP3:
+ search_strings[0] = "vfpv3";
+ // Some old kernels will report vfp for A8, not vfpv3, so we check
for
+ // A8 explicitely. The cpuinfo file report the CPU Part which for
Cortex
+ // A8 is 0xc08.
+ search_strings[1] = "0xc08";
+ search_items = 2;
+ ASSERT(search_items <= max_items);
+ break;
+ case ARMv7:
+ search_strings[0] = "ARMv7" ;
+ search_items = 1;
+ ASSERT(search_items <= max_items);
+ break;
+ default:
+ UNREACHABLE();
+ }
+
+ for (int i = 0; i < search_items; ++i) {
+ if (CPUInfoContainsString(search_strings[i])) {
+ return true;
+ }
+ }
+
+ return false;
+}
#endif // def __arm__
--
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