tarl-b2 at tarl.net
Fri Dec 29 07:13:29 CET 2017
On 2017-Dec-29 01:05 , Tarl Neustaedter wrote:
> Ah! Seeing that structure, the sequence comes down to:
> 0x10 my-space + dup " config-l@" $call-parent
I should mention; that "dup" right before calling " config-l@" suggests
he's going to write a value back very shortly.
This is often done during the probe process, where the PCI drivers
usually fiddle with the BAR to determine its characteristics. The PCI
driver should have already done the write 0xFFFFFFF0 and read it back to
determine the size of the BAR before assigning an address to it, but the
video driver probably needs to read the BAR to determine 32/64 bit. What
it could be expecting to write back is a little confusing to me, at
least at Sun/Oracle, device FCodes were not expected to change the
contents of BARs. Maybe it's going to determine the BAR size and then
put the same value back?
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