[PATCH] Updating legacy code in arm nds

Vipul Nayyar nayyar_vipul at yahoo.com
Fri Aug 23 18:40:56 UTC 2013


I think getting general guidance on ARM will be a great help too. I'm currently working on arm nds. If it's possible, please do try to answer the following questions.

When earlier you converted all ARM bsps, what was the problem you faced with nds ? Something related with libnds ?

I'm following the pattern of work done in gba for nds, since both seem to be similar. So, gba installs the dispatcher with the help of _ARMV4_Exception_interrupt which in turn branches to bsp_interrupt_dispatch while handling an interrupt. Since bsp_interrupt_dispatch being a C function. how is the assembler able to reference it's address ? On the other hand, addressing the same function from interruptdispatcher.s in libnds gives me an undefined reference error. Should I transfer the bsp_interrupt_dispatch installer to start.s or something else can be done to retain the code in the same file. ?


An update, The current work for converting these multiple bsps to generic interrupt support is turning out to be a tad difficult as it requires deep working knowledge of chipset over varied terrain. This might take some time, expanding to more than left GSOC period. But nonetheless, I'll work on it in parallel. I currently feel a need to resume the work for bsp specific file documentation, that we started with initially. As Cynthia Rempel suggested, I'll submit the details of the ideal bsp(lpc24xx) with which function is defined in which file & the list of headers, which was initially compiled earlier over this weekend. I hope to see your active support & guidance for this part. :-) 

Vipul Nayyar 

 From: Sebastian Huber <sebastian.huber at embedded-brains.de>
To: Vipul Nayyar <nayyar_vipul at yahoo.com> 
Cc: Joel Sherrill <joel.sherrill at oarcorp.com>; "rtems-devel at rtems.org" <rtems-devel at rtems.org> 
Sent: Monday, 19 August 2013 5:21 PM
Subject: Re: [PATCH] Updating legacy code in arm nds

Hello Vipul,

I tried to convert all ARM BSPs to the generic IRQ support some in 2010.  The 
not converted BSPs had some special stuff and I had no time to deal with this. 
  I also don't have the time for this now.  I can help you with general ARM 
questions, but I don't look into the details of a BSP/chip.

On 2013-08-18 16:42, Vipul Nayyar wrote:
> Hello,
> The recent patch for arm nds is not entirely error-free. Need some guidance to
> correct the work so far.
> In order to use the generic interrupt support, I've modified the existing
> assembly in libnds & I'm calling bsp_interrupt_dispatch from assembly after
> saving previous context. I'm experiencing an error of undefined reference to
> `bsp_interrupt_dispatch' in assembly. I'm unable to correct it.
> Is the above approach right ? If not, then without using assembly how can I
> save the previous values of registers during context switch in C ?
> Regards
> Vipul Nayyar

Sebastian Huber, embedded brains GmbH

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