Re: [dpdk-stable] [dpdk-dev] [PATCH v4 1/2] eal: make base address hint OS-specific

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 2 Oct 2019 13:41:30 +0200
David Marchand <david.marchand@redhat.com> wrote:

> > +uint64_t eal_get_baseaddr(void)
> > +{
> > +       /*
> > +        * Linux kernel uses a really high address as starting address for
> > +        * serving mmaps calls. If there exists addressing limitations and IOVA
> > +        * mode is VA, this starting address is likely too high for those
> > +        * devices. However, it is possible to use a lower address in the
> > +        * process virtual address space as with 64 bits there is a lot of
> > +        * available space.
> > +        *
> > +        * Current known limitations are 39 or 40 bits. Setting the starting
> > +        * address at 4GB implies there are 508GB or 1020GB for mapping the
> > +        * available hugepages. This is likely enough for most systems, although
> > +        * a device with addressing limitations should call
> > +        * rte_mem_check_dma_mask for ensuring all memory is within supported
> > +        * range.
> > +        */
> > +       return 0x100000000;

Is this going to work right on 32  bit builds where sizeof(uint) == 4
then constants default to 32. Does it need ul or ull suffix (or a cast)?