On 2020-09-24 21:55, Douglas Gilbert wrote: > My code steps down from 1024 KiB elements on failure to 512 KiB and if that > fails it tries 256 KiB. Then it gives up. The log output is consistent with > my analysis. So your stated equality is an inequality when length >= 4 GiB. > There is no promotion of unsigned int nent to uint64_t . > > You can write your own test harness if you don't believe me. The test machine > doesn't need much ram. Without the call to sgl_free() corrected, if it really > did try to get that much ram and failed toward the end, then (partially) > freed up what it had obtained, then you would see a huge memory leak ...> > > Now your intention seems to be that a 4 GiB sgl should be valid. Correct? > Can that check just be dropped? Hi Doug, When I wrote that code, I did not expect that anyone would try to allocate 4 GiB or more as a single scatterlist. Are there any use cases for which a 4 GiB scatterlist works better than two or more smaller scatterlists? Do you agree that many hardware DMA engines do not support transferring 4 GiB or more at once? Thanks, Bart.
