Problem allocating memory in xflash

[Parthasaradhi Nayani]

Hello all,
I have created an external flash memory section in the makefile thus

LDFLAGS += -Wl,--section-start,.exflash=0x850000

and named (defined) this section as XFLASH.

I have a structure "prclkp" of size 32 bytes. When I define

struct prclkp XFLASH PLULOC1[1023];   No error is reported, whereas

struct prclkp XFLASH PLULOC1[1024]; generates an error - "size of array too large"

If the size of the section is 64K, then the above i well within the limit but still the error is popping up. Has this anything to do with sign? Please advice. Thank you.


Regards,
Nayani

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[Tero Sinervo]

Parthasaradhi Nayani wrote:
> I have a structure "prclkp" of size 32 bytes. When I define
>
> struct prclkp XFLASH PLULOC1[1023];   No error is reported, whereas
>
> struct prclkp XFLASH PLULOC1[1024]; generates an error - "size of array too large"

You've probably reached a built-in limit in gcc. It has nothing to do
with the size of your memory section.


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Tero Sinervo


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[Jan Waclawek]

>Parthasaradhi Nayani wrote:
>> I have a structure "prclkp" of size 32 bytes. When I define
>>
>> struct prclkp XFLASH PLULOC1[1023];   No error is reported, whereas
>>
>> struct prclkp XFLASH PLULOC1[1024]; generates an error - "size of array too large"
>
>You've probably reached a built-in limit in gcc. It has nothing to do
>with the size of your memory section.

I've just tried to compile a >64kB initialised variable with "gcc (GCC) 3.4.4 (cygming special)" to confirm this is NOT limit of gcc.
So, it appears to be limit of avr-gcc specifically.

JW


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[Joerg Wunsch]

Jan Waclawek <konfera@...> wrote:

> So, it appears to be limit of avr-gcc specifically.

Sure, it depends from sizeof(int).

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[Jan Waclawek]

>> So, it appears to be limit of avr-gcc specifically.
>
>Sure, it depends from sizeof(int).

Hummm, for me, the relationship is not quite "sure". Can you explain that in more detail, please?
Also, how does it imply the 32k limit on the initialiser and the lack of warning when crossed?

Jan Waclawek


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[Joerg Wunsch]

Jan Waclawek <konfera@...> wrote:

>>Sure, it depends from sizeof(int).

> Hummm, for me, the relationship is not quite "sure". Can you explain
> that in more detail, please?

An array is implicitly (without the option to change it) indexed by
type `int'.  Not `unsigned int', it's `int' -- because negative
indices are explicitly allowed (e.g. to access the previous array
element through a pointer like "a[-1]").

I'm not quite sure why GCC doesn't accept more than __INT_MAX__
*bytes* (as opposed to array elements); perhaps it internally aliases
everything to bytes.

--
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http://www.sax.de/~joerg/                        NIC: JW11-RIPE
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[Parthasaradhi Nayani]

From: Joerg Wunsch <j@...>>

Sure, it depends from sizeof(int).

My array size is 32K bytes and the section is supposed to be 64K right? and is not the built-in limit of a section 64K? Thanks.

Regards
Nayani

start: 0000-00-00 end: 0000-00-00
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[Parthasaradhi Nayani]

From: Jan Waclawek <konfera@...>>

Sure, it depends from sizeof(int).

Hummm, for me, the relationship is not quite "sure". Can you explain that in more detail, please?

I tried to allocate 32K bytes of memory. I am not sure if this is a problem of user defined sections.

Nayani

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