Re: eCos + LPC21xx footprint

[Andrew Lunn <andrew at lunn dot ch>]

On Tue, Nov 16, 2004 at 11:27:39AM +0200, Jani Monoses wrote:
> Hello
> would such a change in arm/vectors.S be to intrusive?
> The 'unused' vector entry is used by LPC's inflash bootloader to detect 
> whether a valid image is present. The value is the checksum of the vector 
> table, fixed since that table doesn't change. If not the download sequence 
> starts else it assumes there's a program and it runs it.
> The Philips hostside (Windows only) downloader modifies the images it 
> downloads on the fly, but on linux I chose to put the value in the image 
> and not add more code to the loader I wrote.
> This means that it does not need to be calculated by every different 
> download method :
> even redboot would not need to do anything extra when writing the flash.
> 
> comments?
> 
> --- orig/packages/hal/arm/arch/current/src/vectors.S
> +++ mod/packages/hal/arm/arch/current/src/vectors.S
> @@ -206,7 +206,7 @@
>          ldr     pc,.software_interrupt          // 0x08 start && software 
>          int
>          ldr     pc,.abort_prefetch              // 0x0C
>          ldr     pc,.abort_data                  // 0x10
> -        .word   0                               // unused
> +#ifdef CYGPKG_HAL_ARM_LPC2XXX
> +        .word   0xB4405F62                      // used by LPC2XXX 
> bootloader, 32 bit
> +#endif
> checksum of the int vectors should be 0
>          ldr     pc,.IRQ                         // 0x18
>          ldr     pc,.FIQ                         // 0x1C

I think i would prefer a CDL option to do this if thats possible. Use
a generic name, say CYGNUM_HAL_ARM_UNUSED_VECTOR which defaults to 0
but a target hal can use a requires statement to set it to a specific
value.

        Andrew