Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 13 Jan 2003 20:20:10 -0500 (EST) | From | "Richard B. Johnson" <> | Subject | Re: Linux 2.4.21-pre3-ac4 |
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On 13 Jan 2003, Benjamin Herrenschmidt wrote:
> On Mon, 2003-01-13 at 22:40, Richard B. Johnson wrote: > > > There is a well-defined procedure for this. Any "read" anywhere > > in the PCI address space, will force all posted writes to complete. > > However, the "read" will not be the data one would obtain after > > the write completes. > > Just to avoid confusion, the above is obviously wrong, the read will > indeed force pending store queues to complete _in order_, the read will > reach the device after the stores are complete and you'll read the value > you would get after the write normally. At least on PCI ;) > > Ben. >
It is not, as you say; "obviously wrong". It is, in fact correct. If you think you will get, as previously stated, the current status by reading the status register of a device, while a posted-write is in-progress, the code is broken. There are warnings all over PCI device hardware specifications about this.
Cheers, Dick Johnson Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips). Why is the government concerned about the lunatic fringe? Think about it.
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