STM32F103C8T6 - problem with FLASH_ErasePage when variable declared in custom section

[DK.3]

Hi All

I am trying to store variable in custom section withn FLASH.

In ld file I have the following

 	.flash_crc (LENGTH(FLASH) + ORIGIN(FLASH) - 1K): 
 	{
 . = ALIGN(4); 	
 *(.flash_crc)
 *(.flash_crc.*)
 . = ALIGN(4); 	
 } >FLASH = 0x00
 

Which (I believe) creates custom section at the last 1K page of 64K FLASH.

Then I am trying to declare a variable in my main.cpp

	volatile uint32_t __attribute__((section(".flash_crc"), used)) __flash_crc;

The map file gives me correct section location at 0x800fc00 and variabke fits inicely inside

.flash_crc 0x000000000800fc00 0x4
 0x000000000800fc00 . = ALIGN (0x4)
 *(.flash_crc)
 .flash_crc 0x000000000800fc00 0x4 ./src/main.o
 0x000000000800fc00 __flash_crc
 *(.flash_crc.*)
 0x000000000800fc04 . = ALIGN (0x4)

In the code I am trying just to erase the FLASH page where the variable is located

 FLASH_PrefetchBufferCmd( FLASH_PrefetchBuffer_Enable);
 FLASH_SetLatency( FLASH_Latency_0);
 FLASH_Status flashStatus;
 FLASH_Unlock();
 flashStatus = FLASH_ErasePage((uint32_t)0x800fc00);
 FLASH_Lock();

flashStatus is set to FLASH_COMPLETE, so I would expect everything is fine, and location 0x800fc00 is filled with 0xff.

In reality this does not happen, and contents of 0x800fc00 stays untouched after ERASE.

Strange enough, if I comment out variable declaration, then everything works fine and 0x800fc00 gets filled with 0xff after ERASE.

The same happens when I am trying to write something to 0x800fc00 using

FLASH_ProgramWord(0x800fc00, 0x12345678)

With variable declared inside .flash_crc section nothing is written, when variable commnted out write succesfully occures.

Any help appreciated, thanks in advance