[SLOF] [PATCH slof] pci-phb: Reimplement dma-map-in/out

Segher Boessenkool segher at kernel.crashing.org
Wed Nov 20 12:05:07 AEDT 2019


On Wed, Nov 20, 2019 at 11:25:20AM +1100, Alexey Kardashevskiy wrote:
> On 20/11/2019 05:10, Segher Boessenkool wrote:
> > On Fri, Nov 15, 2019 at 10:33:58AM +1100, Alexey Kardashevskiy wrote:
> >> I am really not used to "-1000" :-/
> > 
> > -N reads a bit nicer than ~(N-1), but it is the same thing.  I find it
> > easier to read  -1000 and   instead of  fff invert and  but that is for
> > a big part just what you are used to.
> Well, I did not see this being used anywhere else, like, in linux.

It is used a lot in binutils and in GCC, at least.

Linux doesn't use it much, indeed.  It uses the "x & -x" idiom to isolate
the lowest set bit quite a bit, but the "& -align" idiom not often; mostly
a bit in fs/ and in random drivers.


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