Re: [linux-fbdev] Re: readl() and friends and eieio on PPC

On Thu, Aug 12, 1999 at 01:16:14AM -0400, David Edelsohn wrote:

	Is your assumption that you want to provide the infrastructure to
write high-performance device drivers or to write device drivers that
don't require as much expertise and knowledge to produce correct results?

I prefer high-performance drivers. 

There are enough other things (virt_to_bus, ioremap, et al) that are
non-optional that driver writers must learn about for non-peecee
driver programming that proper use of mb/wmb doesn't seem that big a
deal to me.

I guess I personally can afford to be somewhat idealistic in this,
because I only use about 4 drivers -- ncr, aic7xxx, tulip, epic100 --
and the authors of all these drivers have clue.  But the thought of
coddling to folks that can't be bothered to do things Right gives
me hives.



r~

[[ This message was sent via the linuxppc-dev mailing list.  Replies are ]]
[[ not  forced  back  to the list, so be sure to Cc linuxppc-dev if your ]]
[[ reply is of general interest. Please check http://lists.linuxppc.org/ ]]
[[ and http://www.linuxppc.org/ for useful information before posting.   ]]

Richard Henderson [off-list ref] wrote:

I prefer high-performance drivers. 

Sure, so do I.  But when I can get safety as well, for the cost of one
extra cpu cycle per device access, which can probably be overlapped
with the device access anyway, I think it's a good deal.

On alpha, does wmb() stop a subsequent load from being moved ahead of
a previous store?  Or do you have to use mb() to get that effect?

Paul.

[[ This message was sent via the linuxppc-dev mailing list.  Replies are ]]
[[ not  forced  back  to the list, so be sure to Cc linuxppc-dev if your ]]
[[ reply is of general interest. Please check http://lists.linuxppc.org/ ]]
[[ and http://www.linuxppc.org/ for useful information before posting.   ]]