diff options
| -rw-r--r-- | OvmfPkg/Library/PlatformDebugLibIoPort/DebugLibDetect.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/OvmfPkg/Library/PlatformDebugLibIoPort/DebugLibDetect.c b/OvmfPkg/Library/PlatformDebugLibIoPort/DebugLibDetect.c index 81c44eece9..e24cc834c2 100644 --- a/OvmfPkg/Library/PlatformDebugLibIoPort/DebugLibDetect.c +++ b/OvmfPkg/Library/PlatformDebugLibIoPort/DebugLibDetect.c @@ -17,13 +17,25 @@ #include "DebugLibDetect.h"
//
+// Set to TRUE if the debug I/O port has been checked
+//
+STATIC BOOLEAN mDebugIoPortChecked = FALSE;
+
+//
// Set to TRUE if the debug I/O port is enabled
//
STATIC BOOLEAN mDebugIoPortFound = FALSE;
/**
- This constructor function checks if the debug I/O port device is present,
- caching the result for later use.
+ This constructor function must not do anything.
+
+ Some modules consuming this library instance, such as the DXE Core, invoke
+ the DEBUG() macro before they explicitly call
+ ProcessLibraryConstructorList(). Therefore the auto-generated call from
+ ProcessLibraryConstructorList() to this constructor function may be preceded
+ by some calls to PlatformDebugLibIoPortFound() below. Hence
+ PlatformDebugLibIoPortFound() must not rely on anything this constructor
+ could set up.
@retval RETURN_SUCCESS The constructor always returns RETURN_SUCCESS.
@@ -34,12 +46,12 @@ PlatformDebugLibIoPortConstructor ( VOID
)
{
- mDebugIoPortFound = PlatformDebugLibIoPortDetect();
return RETURN_SUCCESS;
}
/**
- Return the cached result of detecting the debug I/O port device.
+ At the first call, check if the debug I/O port device is present, and cache
+ the result for later use. At subsequent calls, return the cached result.
@retval TRUE if the debug I/O port device was detected.
@retval FALSE otherwise
@@ -51,5 +63,9 @@ PlatformDebugLibIoPortFound ( VOID
)
{
+ if (!mDebugIoPortChecked) {
+ mDebugIoPortFound = PlatformDebugLibIoPortDetect ();
+ mDebugIoPortChecked = TRUE;
+ }
return mDebugIoPortFound;
}
|