Re: user space writel() etc. in 2.2.2

Jes Sorensen (Jes.Sorensen@cern.ch)
05 Mar 1999 18:14:00 +0100


>>>>> "Alan" == Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

>> Alpha + sparse memory + mmap'ed frame buffer + mmap'ed control
>> registers.
>>
>> I am not that familiar with the sparse mem but I doubt mmap() has a
>> kludge to get around it (I found out the hard way why readl/writel
>> is needed when porting the AceNIC driver to run an Avanti).

Alan> The Alpha functions sometimes use a kernel jump table. Im sure
Alan> thats really going to work well from user space. The moment you
Alan> go digging into devices directly from user space you lose
Alan> portability.

Hmmm, good point - I wonder how the XFree people solved this for the
Alpha X servers.

Jes

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