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Lu" Date: Thu, 15 Feb 2024 14:05:32 -0800 Message-ID: Subject: Re: [PATCH v5 1/2] x86-64: Save APX and Tile registers in ld.so trampoline To: Florian Weimer Cc: libc-alpha@sourceware.org, goldstein.w.n@gmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-3014.4 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Thu, Feb 15, 2024 at 1:39=E2=80=AFPM Florian Weimer = wrote: > > * Florian Weimer: > > > * H. J. Lu: > > > >> Add APX registers to STATE_SAVE_MASK so that APX and Tile registers ar= e > >> saved in ld.so trampoline. This fixes BZ #31371. > > > > First APX is confusing? What do you suggest? > > > > What's the impact on xsave_state_size and xsave_state_full_size? > > I'm worried that the loader trampoline now overflows small stacks. > > We used to have such problems in the past. > > It adds 8,256 bytes on one AMX-capable machine. This will impact > compatibility with existing software. Stack usage is increased even if > the application does not use AMX at all. Also AMX may be enabled much later. > I suggest to use a mechanism like STO_AARCH64_VARIANT_PCS to deal with > AMX, and only add the APX flag for now. > I will drop Tile registers. --=20 H.J.