On Tue, Nov 28, 2023 at 09:27:08AM +0200, Rémi Denis-Courmont wrote: > > > Le 28 novembre 2023 01:22:14 GMT+02:00, Michael Niedermayer > <mich...@niedermayer.cc> a écrit : > >On Mon, Nov 27, 2023 at 05:46:40PM +0200, Rémi Denis-Courmont wrote: > >[...] > >> Also FWIW, RV broke due to misaligned accesses and illegal vector types > >> that > >> QEMU tolerated. That is rather an argument against QEMU than against this > >> MR > >> but still. > > > >has someone reported this to qemu ? > >(seems like a bug) > > It's not a bug. The specification leaves those cases *undefined*. QEMU > supports them because they can, and adding sanity checks would just slow > stuff down. > > Also generally QEMU TCG policy seems to be maximize perf and compatibility, > not formal correctness.
I think i read somewhere that recent qemu supposedly checks alignment on arm more completely. But i couldnt quickly find a official statement about that But either way, qemu could emit such code optionally when it is used for testing. Which is one of the things people use qemu for. So IMHO it would make sense for qemu to detect cases that are undefined even if for no other reason than to emulate the hw more exactly. If this is not done, qemu can be detected and code could refuse or fail to run thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Modern terrorism, a quick summary: Need oil, start war with country that has oil, kill hundread thousand in war. Let country fall into chaos, be surprised about raise of fundamantalists. Drop more bombs, kill more people, be surprised about them taking revenge and drop even more bombs and strip your own citizens of their rights and freedoms. to be continued
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