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[2403:580b:97e8:0:82ce:f179:8a79:69f4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-20710e352d8sm40944425ad.72.2024.09.09.21.54.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Sep 2024 21:54:40 -0700 (PDT) From: Alistair Francis X-Google-Original-From: Alistair Francis To: qemu-devel@nongnu.org, alex.bennee@linaro.org, peter.maydell@linaro.org Cc: Bin Meng , palmer@dabbelt.com, liwei1518@gmail.com, zhiwei_liu@linux.alibaba.com, alistair23@gmail.com, qemu-riscv@nongnu.org, Alistair Francis , Paolo Bonzini , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , atishp@rivosinc.com, dbarboza@ventanamicro.com, Alistair Francis , Thomas Huth Subject: [PATCH v4 1/2] hw/char: riscv_htif: Use blocking qemu_chr_fe_write_all Date: Tue, 10 Sep 2024 14:54:18 +1000 Message-ID: <20240910045419.1252277-2-alistair.francis@wdc.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910045419.1252277-1-alistair.francis@wdc.com> References: <20240910045419.1252277-1-alistair.francis@wdc.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::62a; envelope-from=alistair23@gmail.com; helo=mail-pl1-x62a.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The current approach of using qemu_chr_fe_write() and ignoring the return values results in dropped characters [1]. Ideally we want to report FIFO status to the guest, but the HTIF isn't a real UART, so we don't really have a way to do that. Instead let's just use qemu_chr_fe_write_all() so at least we don't drop characters. 1: https://gitlab.com/qemu-project/qemu/-/issues/2114 Signed-off-by: Alistair Francis Reviewed-by: Daniel Henrique Barboza Reviewed-by: Thomas Huth Reviewed-by: Philippe Mathieu-Daudé --- hw/char/riscv_htif.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c index 9bef60def1..d40b542948 100644 --- a/hw/char/riscv_htif.c +++ b/hw/char/riscv_htif.c @@ -218,7 +218,11 @@ static void htif_handle_tohost_write(HTIFState *s, uint64_t val_written) tswap64(syscall[3]) == HTIF_CONSOLE_CMD_PUTC) { uint8_t ch; cpu_physical_memory_read(tswap64(syscall[2]), &ch, 1); - qemu_chr_fe_write(&s->chr, &ch, 1); + /* + * XXX this blocks entire thread. Rewrite to use + * qemu_chr_fe_write and background I/O callbacks + */ + qemu_chr_fe_write_all(&s->chr, &ch, 1); resp = 0x100 | (uint8_t)payload; } else { qemu_log_mask(LOG_UNIMP, @@ -237,7 +241,11 @@ static void htif_handle_tohost_write(HTIFState *s, uint64_t val_written) return; } else if (cmd == HTIF_CONSOLE_CMD_PUTC) { uint8_t ch = (uint8_t)payload; - qemu_chr_fe_write(&s->chr, &ch, 1); + /* + * XXX this blocks entire thread. Rewrite to use + * qemu_chr_fe_write and background I/O callbacks + */ + qemu_chr_fe_write_all(&s->chr, &ch, 1); resp = 0x100 | (uint8_t)payload; } else { qemu_log("HTIF device %d: unknown command\n", device);