config: Add function to check if fw_cfg exists

It was found qemu_get_present_cpus_count may return impossible
number of cpus because of not checking if fw_cfg exists before
using it. That may lead to undefined behavior of emulator,
in particular Bochs that freezes.

Signed-off-by: Petr Berky <petr.berky@email.cz>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/fw/paravirt.h b/src/fw/paravirt.h
index 16f3d9a6..a14d83e1 100644
--- a/src/fw/paravirt.h
+++ b/src/fw/paravirt.h
@@ -49,6 +49,7 @@ static inline int runningOnKVM(void) {
 // QEMU_CFG_DMA ID bit
 #define QEMU_CFG_VERSION_DMA    2
 
+int qemu_cfg_enabled(void);
 int qemu_cfg_dma_enabled(void);
 void qemu_preinit(void);
 void qemu_platform_setup(void);