Re: [Qemu-devel] [PATCH] target-arm: add Faraday ARMv5TE processors support

[蘇國榮]

>> * ARMv5TE series (FA606TE, FA626TE, FA616TE, FA726TE)
>> 
>>     All the single core RISC listed above are included in this patch.
>>     And there are two Faraday CP15 extensions (AUX and I/D-Scratchpad)
>>     have been implemented as NOP.

>Is a NOP appropriate?  Should you at least read the value back?

Not necessary, because

1. Auxiliary Control Register:
  It's used to alter the cache behaviors which is not important to QEMU.
  For example, it could:
  a) Turn-off the d-cache write allocations upon wirte missed.
    (By default, FA626TE is configured as Read/Write Allocation for D-Cache; 
     which leads to a very poor memcpy speed while compared with general ARM 
processors 
     which are Read-Allocation Only by default)
2. I/D-Scratchpad Configuration Register:
  It's used to setup a memory region for I/D-scratchpad memory; A 
I/D-scratchpad is a dedicated 
  cache memory for a specific region of code/data(I/D), while I/D-caches work 
with random locality.
  And thus, it's also meaningless to QEMU.

The reason why I add these two CP15 instructions to QEMU, is to prevent it 
hangs up without any notifications
upon executing these instructions; I've seen such issue at QEMU-1.3.0, so I 
think it would be better
if we could put these dummy registers into the helper.c


Best Regards
Dante Su

-----Original Message-----
From: Paul Brook [mailto:address@hidden 
Sent: Friday, January 18, 2013 5:45 PM
To: Dante Kuo-Jung Su(蘇國榮)
Cc: address@hidden; address@hidden
Subject: Re: [PATCH] target-arm: add Faraday ARMv5TE processors support

> * ARMv5TE series (FA606TE, FA626TE, FA616TE, FA726TE)
> 
>     All the single core RISC listed above are included in this patch.
>     And there are two Faraday CP15 extensions (AUX and I/D-Scratchpad)
>     have been implemented as NOP.

Is a NOP appropriate?  Should you at least read the value back?

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This sort of disclaimer is completely inappropriate for public mailing lists, 
and I'm unwilling to touch anything subject to these restrictions.
As instructed I have deleted all your other email unread.

Paul

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Thank you for your cooperation.
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