Re: [Openvortex-dev] Re: Re: [ALSA - driver 0001138]: errors when installing au8820 modules

Igor Kovalenko
2005-06-07T17:38:12Z

Alien wrote:
> Op dinsdag 7 juni 2005 19:05, schreef Igor Kovalenko:
>
>>Takashi Iwai wrote:
>>
>>>At Tue, 7 Jun 2005 17:16:02 +0200,
>>>
>>>Alien wrote:
>>>
>>>>[1 <text/plain; iso-8859-1 (quoted-printable)>]
>>>>
>>>>Op dinsdag 7 juni 2005 17:05, schreef Raymond:
>>>>
>>>>>The patch (diff11.diff) cause segmenation fault on my 32bit machine
>>>>>during /etc/init.d/alsasound start
>>>>>
>>>>>http://savannah.nongnu.org/patch/?func=detailitem&item_id=3948
>>>>>
>>>>>Do anyone know why readl() and writel() behave different in i386
>>>>>(32bits) and AMD64 (64bits) ?
>>>>>
>>>>>http://sourceforge.net/mailarchive/message.php?msg_id=10773530
>>>>>
>>>>>
>>>>>#ifndef CONFIG_X86_64
>>>>>
>>>>>#define hwread(x,y) readl((x)+((y)>>2))
>>>>>#define hwwrite(x,y,z) writel((z),(x)+((y)>>2))
>>>>>
>>>>>#else
>>>>>
>>>>>#define hwread(x,y) readl((x)+(y))
>>>>>#define hwwrite(x,y,z) writel((z),(x)+(y))
>>>>>
>>>>>#endif
>>>>
>>>>that doesn't look good, unless the mmio is void* in 32bit and unsigned
>>>>long* in x86_64...
>>>>
>>>>'unsigned long* mmio' should be preferred and together with '#define
>>>>hwread(x,y) readl((x)+(y))' , this works for both platforms
>>>
>>>I guess using "unsigned long" for both architectures is broken, too.
>>>Should be "u32" to be arch-independent.
>>
>>I strongly believe readl() and writel() on x86_64 does 32 bit reads/writes.
>>(checked linux-2.6.12-rc5). Therefore reads/writes are of correct size with
>>that patch - should be something different.
>
>
> i know that does not work!
>
> when i started doing this, i got segfaults because of the >>2 .
>
> readl and writel do long operations as evidenced by the 'l'
>
> i know this seems weird, but this is memory-mapped, and appearantly it's
> memory mapped to long, anyway; when i do 'unsigned long* mmio' and i use
> readl and writel without any bitshifts, it works...
>
> you may believe what you want, but i _know_ that on x86_64, i _NEED_ unsigned
> long* mmio and no bitshifting to get this to work.
>
> maybe the problem lies with writel and readl to begin with, maybe if you wrote
> an int, it would work...
>
> AL13N

OK, then let's put it this way: change to void* and removal of shifts is to make
address operations correct. That is the address itself is at the same offset on
all arches. Then readl/writel just do 32 bit read/write which is what we need.
May be it is the mapping is wrong?

Please check if you applied the patch correctly - I suspect you used different
kernel version and patch may have missed some points... BTW the segfault (oops)
report would be handy.

--
Kind regards,
Igor V. Kovalenko

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