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SubjectRe: Safety of IRQ during i/o

On Wed, 24 Jul 2002, Pete Zaitcev wrote:

> >[...]
> > I would think that this would be safe when using DMA, and likely to be
> > safe for PIO and more recent chipsets, but I wouldn't want to actually
> > tell anyone that.
>
> A little story from OLS. I have a 486/75 laptop, which can only
> do PIO. It always was losing characters evern on 9600 baud on its
> serial port, and I thought it was simply broken for five years.

:-)

> A guy who did a security talk showed me that doing hdparm -u
> fixes the problem. Apparently, the lappy has a non-buffering UART.
>
> So, it seems that hdparm -u is a very useful thing for obsotele
> boxes. If you do DMA, you probably do not care.

Yup, for PIO unmask (if possible) is a must.

--bzolnier

> -- Pete

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