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136 lines
4.1 KiB
136 lines
4.1 KiB
Subject: no sysrq on Cell QS21/QS22 serial console
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From: olh@suse.de
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References: 422987 - LTC47675, 96313 - LTC16841
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Patch-mainline: not yet
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a POWER4 system in 'full-system-partition' mode has the console device
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on ttyS0. But the user interface to the Linux system console may still
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be on the hardware management console (HMC). If this is the case, there
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is no way to send a break to trigger a sysrq.
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Other setups do already use 'ctrl o' to trigger sysrq. This includes iSeries
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virtual console on tty1 or hvc0, and pSeries LPAR console on hvc0 or hvsi0.
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This affects also Cell Blades QS2x.
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To limit the 'ctrl o' only to the affected systems, query the model property
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in the device-tree. The patch makes the serial console not-eight-bit-clean.
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Booting with 'console=ttyS0' will disable 'ctrl o', it is only enabled
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with console autodetection.
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'ctrl o' is currently mapped to 'flush output', see 'stty -a'
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Signed-off-by: Olaf Hering <olh@suse.de>
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---
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arch/powerpc/include/asm/serial.h | 6 ++++
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arch/powerpc/kernel/legacy_serial.c | 52 ++++++++++++++++++++++++++++++++++++
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drivers/tty/serial/8250.c | 6 ++++
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3 files changed, 64 insertions(+)
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--- a/arch/powerpc/include/asm/serial.h
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+++ b/arch/powerpc/include/asm/serial.h
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@@ -15,6 +15,12 @@
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/* Default baud base if not found in device-tree */
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#define BASE_BAUD ( 1843200 / 16 )
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+#if defined(SUPPORT_SYSRQ) && defined(CONFIG_PPC_PSERIES)
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+#undef arch_8250_sysrq_via_ctrl_o
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+extern int do_sysrq_via_ctrl_o;
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+#define arch_8250_sysrq_via_ctrl_o(ch, port) ((ch) == '\x0f' && do_sysrq_via_ctrl_o && uart_handle_break((port)))
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+#endif
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+
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#ifdef CONFIG_PPC_UDBG_16550
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extern void find_legacy_serial_ports(void);
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#else
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--- a/arch/powerpc/kernel/legacy_serial.c
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+++ b/arch/powerpc/kernel/legacy_serial.c
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@@ -495,6 +495,55 @@ device_initcall(serial_dev_init);
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#ifdef CONFIG_SERIAL_8250_CONSOLE
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+#if defined(CONFIG_PPC_PSERIES) && defined(CONFIG_SERIAL_8250_CONSOLE)
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+/*
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+ * Handle the SysRq ^O Hack also via ttyS0 on POWER4 systems
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+ * but only on the system console, see asm/serial.h
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+ * If they run in FullSystemPartition mode, the firmware console comes in via ttyS0
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+ * But BREAK does not work via the HMC, to trigger sysrq.
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+ * The same is required for Cell blades
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+ */
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+int do_sysrq_via_ctrl_o;
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+static const char __initdata *need_ctrl_o[] = {
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+ "IBM,079", /* QS2x */
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+ "IBM,0792-32G", /* QS21 */
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+ "IBM,0793-2RZ", /* QS22 */
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+ "IBM,7040-681", /* p690 */
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+ "IBM,7040-671", /* p670 */
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+ "IBM,7039-651", /* p655 */
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+ "IBM,7038-6M2", /* p650 */
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+ "IBM,7028-6E4", /* p630 tower */
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+ "IBM,7028-6C4", /* p630 rack */
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+ "IBM,7029-6E3", /* p615 tower */
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+ "IBM,7029-6C3", /* p615 rack */
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+ NULL
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+};
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+static void __init detect_need_for_ctrl_o(void)
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+{
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+ struct device_node *root;
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+ const char *model, *p;
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+ int i;
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+
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+ root = of_find_node_by_path("/");
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+ if (!root)
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+ return;
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+ model = of_get_property(root, "model", NULL);
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+ if (model) {
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+ i = 0;
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+ while (need_ctrl_o[i]) {
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+ p = need_ctrl_o[i];
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+ if (strncmp(p, model, strlen(p)) == 0) {
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+ do_sysrq_via_ctrl_o = 1;
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+ DBG("Enable sysrq via CTRL o on model %s\n", model);
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+ break;
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+ }
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+ i++;
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+ }
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+ }
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+ of_node_put(root);
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+}
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+#endif
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+
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/*
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* This is called very early, as part of console_init() (typically just after
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* time_init()). This function is respondible for trying to find a good
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@@ -563,6 +612,9 @@ static int __init check_legacy_serial_co
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if (i >= legacy_serial_count)
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goto not_found;
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+#if defined(CONFIG_PPC_PSERIES) && defined(CONFIG_SERIAL_8250_CONSOLE)
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+ detect_need_for_ctrl_o();
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+#endif
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of_node_put(prom_stdout);
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DBG("Found serial console at ttyS%d\n", offset);
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--- a/drivers/tty/serial/8250.c
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+++ b/drivers/tty/serial/8250.c
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@@ -102,6 +102,8 @@ static unsigned int skip_txen_test; /* f
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#define CONFIG_SERIAL_MANY_PORTS 1
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#endif
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+#define arch_8250_sysrq_via_ctrl_o(a,b) 0
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+
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/*
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* HUB6 is always on. This will be removed once the header
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* files have been cleaned.
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@@ -1423,7 +1425,11 @@ receive_chars(struct uart_8250_port *up,
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do {
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if (likely(lsr & UART_LSR_DR))
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+ {
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ch = serial_inp(up, UART_RX);
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+ if (arch_8250_sysrq_via_ctrl_o(ch, &up->port))
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+ goto ignore_char;
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+ }
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else
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/*
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* Intel 82571 has a Serial Over Lan device that will
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