On Tue, Feb 20, 2018 at 11:05:22AM +0000, Ard Biesheuvel wrote:
> +/**
> + Prints an assert message containing a filename, line number, and
> description.
> + This may be followed by a breakpoint or a dead loop.
> +
> + Print a message of the form "ASSERT <FileName>(<LineNumber>):
> <Description>\n"
> + to the debug output device. If DEBUG_PROPERTY_ASSERT_BREAKPOINT_ENABLED
> bit
> + of PcdDebugProperyMask is set then CpuBreakpoint() is called. Otherwise, if
> + DEBUG_PROPERTY_ASSERT_DEADLOOP_ENABLED bit of PcdDebugProperyMask is set
> then
> + CpuDeadLoop() is called. If neither of these bits are set, then this
> function
> + returns immediately after the message is printed to the debug output
> device.
> + DebugAssert() must actively prevent recursion. If DebugAssert() is called
> + while processing another DebugAssert(), then DebugAssert() must return
> + immediately.
> +
> + If FileName is NULL, then a <FileName> string of "(NULL) Filename" is
> printed.
> + If Description is NULL, then a <Description> string of "(NULL)
> Description" is
> + printed.
> +
> + @param FileName The pointer to the name of the source file that
> generated
> + the assert condition.
> + @param LineNumber The line number in the source file that generated the
> + assert condition
> + @param Description The pointer to the description of the assert
> condition.
> +
> +**/
> +VOID
> +EFIAPI
> +DebugAssert (
> + IN CONST CHAR8 *FileName,
> + IN UINTN LineNumber,
> + IN CONST CHAR8 *Description
> + )
> +{
> + CHAR8 Buffer[MAX_DEBUG_MESSAGE_LENGTH];
> +
> + if (!mEfiAtRuntime) {
> + //
> + // Generate the ASSERT() message in Ascii format
> + //
> + AsciiSPrint (Buffer, sizeof (Buffer), "ASSERT [%a] %a(%d): %a\n",
> + gEfiCallerBaseName, FileName, LineNumber, Description);
> +
> + //
> + // Send the print string to the Console Output device
> + //
> + SerialPortWrite ((UINT8 *)Buffer, AsciiStrLen (Buffer));
> + }
> +
> + //
> + // Generate a Breakpoint, DeadLoop, or NOP based on PCD settings
> + //
> + if ((FixedPcdGet8 (PcdDebugPropertyMask) &
> + DEBUG_PROPERTY_ASSERT_BREAKPOINT_ENABLED) != 0) {
> + CpuBreakpoint ();
> + } else if ((FixedPcdGet8 (PcdDebugPropertyMask) &
> + DEBUG_PROPERTY_ASSERT_DEADLOOP_ENABLED) != 0) {
> + CpuDeadLoop ();
> + }
Hmm ... I know this does not fundamentally change the behaviour of the
existing implementation, but if we're looking to improve runtime
behaviour, we've just gone from generating a runtime fault to silently
freezing (if BREAKPOINT_ENABLED or DEADLOOP_ENABLED).
What do breakpoint/deadloop mean in a runtime context anyway - do we
not need to halt _all_ running cores?
I don't see an obvious "right way" solution here, and this only
affects DEBUG builds. Possible ways of handling this that I can think
of include:
- Don't respect BREAKPOINT/DEADLOOP if at runtime.
- Respect BREAKPOINT/DEADLOOP and disable all cores.
- Take ownership back of the system and re-enable 1:1 mapping so
messages can be printed.
/
Leif
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