On Mon, 27 Nov 2017 12:02:55 +0100 Cornelia Huck <coh...@redhat.com> wrote:
> On Mon, 27 Nov 2017 07:59:36 +0100 > Thomas Huth <th...@redhat.com> wrote: > > > On 25.11.2017 14:49, Pierre Morel wrote: > > > On 24/11/2017 07:19, Yi Min Zhao wrote: > > >> > > >> > > >> 在 2017/11/23 下午8:18, Thomas Huth 写道: > > >>> On 23.11.2017 13:07, Yi Min Zhao wrote: > > > >>>> Another question, does 'cpu' in cpu_to_le**() or le**_to_cpu() mean the > > >>>> host endianess? > > >>> Yes, the "cpu" in cpu_to_le or le_to_cpu means the host, indeed. It's > > >>> confusing :-/ > > >>> > > >>>> If the answers to upper two questions are yes, we actually need handle > > >>>> two cases. > > >>>> 1) For pcilg, we need to translate the data to little-endian, thus > > >>>> cpu_to_le**(). > > >>>> 2) For pcistg, we need to translate the data to host endianess, thus > > >>>> le**_to_cpu(). > > >>> I think we've got to byte-swap if the host is big endian (s390x), but > > >>> not if the host is little endian (x86 with TCG). > > > > > > Here is my comprehension of this funny swapping: > > > > > > - TCG for a BE guest and a le host swap bytes because if we do (register > > > & 0x01) in the zPCI interception code it must work what ever the > > > endianess is. > > > > Uhhh, I might have missed that the value has already been byte-swapped > > once by TCG for env->regs[r1] ... > > Now I'm pretty much completely confused ... sorry for the noise if I was > > wrong... I think it's best you ignore my comment for now (i.e. go with > > bswapXX() instead of le_to_cpuXX()), and if we later wire up zPCI with > > TCG, we still can fix this if necessary. > > I'll try my current pci/tcg patches on LPAR with this (or a v4) on top. > If it works there (it doesn't yet on my laptop), we do have a > endianness issue... (unfortunately, the reverse isn't true.) It does not look too bad: I can get a nice enP1p0s0 device from a virtio-net-pci with my tcg patches on my laptop (with these patches as well, of course). So, endianness is likely mostly fine. > > I'll post my pci/tcg patches once I get it mostly working (and it does > not look like a horror from the crypt anymore). Time to get out the make up kit for these.
