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Date: Sun, 19 Dec 2010 13:37:58 -0600
From: Bob Breuer <breuerr@mc.net>
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Subject: Re: [Qemu-devel] Re: [PATCH] sparc32: ledma extra registers
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To: =?ISO-8859-1?Q?Andreas_F=E4rber?= <andreas.faerber@web.de>
Cc: Blue Swirl <blauwirbel@gmail.com>, QEMU Developers <qemu-devel@nongnu.org>

Andreas Färber wrote:
> Am 18.12.2010 um 19:53 schrieb Blue Swirl:
>
>> On Sat, Dec 18, 2010 at 5:09 PM, Bob Breuer <breuerr@mc.net> wrote:
>>> ledma has 0x20 bytes of registers according to OBP, and at least
>>> Solaris9
>>> reads the 5th register which is beyond what we've mapped.  So let's
>>> setup
>>> a flag (inspired by a previous patch from Blue Swirl) to identify ledma
>>> from espdma, and map another 16 bytes of registers which return 0.
>>>
>>> Signed-off-by: Bob Breuer <breuerr@mc.net>
>
> I'm not familar with that part of code but...
>
>>> diff --git a/hw/sparc32_dma.c b/hw/sparc32_dma.c
>>> index e78f025..56be8c8 100644
>>> --- a/hw/sparc32_dma.c
>>> +++ b/hw/sparc32_dma.c
>
>>> @@ -165,6 +169,9 @@ static uint32_t dma_mem_readl(void *opaque,
>>> target_phys_addr_t addr)
>>>     DMAState *s = opaque;
>>>     uint32_t saddr;
>>>
>>> +    if (s->is_ledma && (addr > DMA_MAX_REG_OFFSET)) {
>>> +        return 0; /* extra mystery register(s) */
>
> Wouldn't it be a good idea to trace these "mystery" reads...
>
>>> +    }
>>>     saddr = (addr & DMA_MASK) >> 2;
>>>     trace_sparc32_dma_mem_readl(addr, s->dmaregs[saddr]);
>>>     return s->dmaregs[saddr];
>>> @@ -175,6 +182,9 @@ static void dma_mem_writel(void *opaque,
>>> target_phys_addr_t addr, uint32_t val)
>>>     DMAState *s = opaque;
>>>     uint32_t saddr;
>>>
>>> +    if (s->is_ledma && (addr > DMA_MAX_REG_OFFSET)) {
>>> +        return; /* extra mystery register(s) */
>
> ...and writes? We return just before the tracepoints fire.
>

Ok, I'll put together a patch to add the trace calls just before the
returns.  How about I also call it undocumented instead of mystery. 
None of the BSD's or Linux know about or use anything beyond the 4
registers.

Blue, do you know of a mirror for the documents at
http://wikis.sun.com/display/FOSSdocs/Home ?  The pdfs there seem to
have gone missing, and maybe there might be something in the macio
documentation.

Bob