[avr-libc-dev] [bug #40206] SP initialization in startup code for xmegas is inconsistent with compiler generated initialization in function prologue

[Senthil Kumar Selvaraj]

URL:
  <http://savannah.nongnu.org/bugs/?40206>

                 Summary: SP initialization in startup code for xmegas is
inconsistent with compiler generated initialization in function prologue
                 Project: AVR C Runtime Library
            Submitted by: saaadhu
            Submitted on: Tue 08 Oct 2013 12:24:16 PM GMT
                Category: Library
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Startup code
                  Status: None
        Percent Complete: 0%
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 1.8.0
           Fixed Release: None

    _______________________________________________________

Details:

gcrt1.S writes SPH before SPL for all devices. For xmegas, the compiler,
however, writes SPL before SPH. This is to avoid occurence of interrupts after
the writing of SPH but before the writing of SPL; the hardware disables
interrupts for four instructions after the write to SPL.

Also, things like writing to the CCP first up in main fail silently because of
the reversed order of writing to the SP (when there are less than 4
instructions separating the write to SPL and the write to CCP).

The attached patch (patch #1) makes the startup code write to SPL and then SPH
for xmegas, making it consistent with what the compiler does for function
prologues.



    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Tue 08 Oct 2013 12:24:16 PM GMT  Name: fix_sp_write_xmega.patch  Size:
707B   By: saaadhu

<http://savannah.nongnu.org/bugs/download.php?file_id=29326>

    _______________________________________________________

Reply to this item at:

  <http://savannah.nongnu.org/bugs/?40206>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.nongnu.org/