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uVisor: Standardize available legacy heap and stack #3692

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Merged
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Feb 9, 2017
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uVisor: Standardize available legacy heap and stack #3692

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12 changes: 9 additions & 3 deletions ...eescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/device/TOOLCHAIN_GCC_ARM/MK64FN1M0xxx12.ld
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Original file line number Diff line number Diff line change
Expand Up @@ -53,9 +53,15 @@ ENTRY(Reset_Handler)

__ram_vector_table__ = 1;

/* Heap 1/4 of ram and stack 1/8 */
__stack_size__ = 0x8000;
__heap_size__ = 0x10000;
/* With the RTOS in use, this does not affect the main stack size. The size of
* the stack where main runs is determined via the RTOS. */
__stack_size__ = 0x400;
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Looks fine for mbed 5. However, in case RTOS is not used (mbed 2), this radically decreasing stack size for MCU like k64f.

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I agree, without RTOS, the stack for the main function is reduced a lot. With RTOS, having this be large is a waste of memory, as the user application can never use this RAM (the RTOS uses it for its stack).

It's almost like we need two different linker scripts, one for with RTOS and one for without, unless we can come up with a good balanced number that isn't too bad of a choice for either platform. Any suggestions?

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The linker scripts already contain a conditional assignment like the following:

HEAP_SIZE  = DEFINED(__heap_size__)  ? __heap_size__  : 0x0400;
STACK_SIZE = DEFINED(__stack_size__) ? __stack_size__ : 0x0400;

so we could define those symbols somewhere else. In that way we can also define them depending on RTOS being used or not. @0xc0170 do you agree? What's the best place to place those definitions?

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Actually, doesn't the stack just start at the top of SRAM and grow down until it hits the heap? So, this would be a minimum stack size with mbed 2.

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True. So this should not be an issue @0xc0170

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Yes, I believe so.

LGTM


/* This is the guaranteed minimum available heap size for an application. When
* uVisor is enabled, this is also the maximum available heap size. The
* HEAP_SIZE value is set by uVisor porters to balance the size of the legacy
* heap and the page heap in uVisor applications. */
__heap_size__ = 0x6000;

HEAP_SIZE = DEFINED(__heap_size__) ? __heap_size__ : 0x0400;
STACK_SIZE = DEFINED(__stack_size__) ? __stack_size__ : 0x0400;
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12 changes: 9 additions & 3 deletions targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F429xI/device/TOOLCHAIN_GCC_ARM/STM32F429xI.ld
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Original file line number Diff line number Diff line change
@@ -1,8 +1,14 @@
M_VECTOR_RAM_SIZE = 0x400;

/* Heap: 1/4 of RAM. Stack: 1/8 of RAM. */
STACK_SIZE = 0x6000;
HEAP_SIZE = 0xC000;
/* With the RTOS in use, this does not affect the main stack size. The size of
* the stack where main runs is determined via the RTOS. */
STACK_SIZE = 0x400;

/* This is the guaranteed minimum available heap size for an application. When
* uVisor is enabled, this is also the maximum available heap size. The
* HEAP_SIZE value is set by uVisor porters to balance the size of the legacy
* heap and the page heap in uVisor applications. */
HEAP_SIZE = 0x6000;

/* Specify the memory areas */
MEMORY
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9 changes: 8 additions & 1 deletion ...Silicon_Labs/TARGET_EFM32/TARGET_EFM32GG/device/TARGET_1024K/TOOLCHAIN_GCC_ARM/efm32gg.ld
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Original file line number Diff line number Diff line change
Expand Up @@ -9,8 +9,15 @@
/* Version 4.2.0 */
/* */

/* With the RTOS in use, this does not affect the main stack size. The size of
* the stack where main runs is determined via the RTOS. */
STACK_SIZE = 0x400;
HEAP_SIZE = 0xC00;

/* This is the guaranteed minimum available heap size for an application. When
* uVisor is enabled, this is also the maximum available heap size. The
* HEAP_SIZE value is set by uVisor porters to balance the size of the legacy
* heap and the page heap in uVisor applications. */
HEAP_SIZE = 0x6000;

MEMORY
{
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