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Date: Sat, 1 Oct 2022 00:41:30 +0200
From: Helge Deller <deller@....de>
To: John Ogness <john.ogness@...utronix.de>
Cc: Helge Deller <deller@....de>, Petr Mladek <pmladek@...e.com>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org,
"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-parisc@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH printk 11/18] printk: Convert console_drivers list to
hlist
* John Ogness <john.ogness@...utronix.de>:
> On 2022-09-30, Helge Deller <deller@....de> wrote:
> >> I know that it is all hope for good. But there is also a race between
> >> the hlist_empty() and hlist_entry().
> >
> > I wonder if pdc_console() is still needed as it is today. When this
> > was written, early_console and such didn't worked for parisc as it
> > should. That's proably why we have this register/unregister in here.
> >
> > Would it make sense, and would we gain something for this
> > printk-series, if I'd try to convert pdc_console to a standard
> > earlycon or earlyprintk device?
>
> Having an earlycon or earlyprintk device will not really help you here
> since those drivers will have already unregistered.
>
> However, once we get the new atomic/kthread interface available, it
> certainly would be useful to implement the pdc_console as an atomic
> console.
My idea was to drop most of the pdc console, so that patch #8 and parts
of patch #11 of the printk patch series could be dropped and you won't
need to take care of those parts when introducing the printk
threaded/atomic printing changes.
See patch below. Basically it drops all of the offending code.
I haven't yet checked it into my parisc for-next tree to not break
something.
Helge
From 5b697874e10729136ce7dd7b362b276f35fae56d Mon Sep 17 00:00:00 2001
From: Helge Deller <deller@....de>
Date: Sat, 1 Oct 2022 00:32:07 +0200
Subject: [PATCH] parisc: Drop PDC console and convert it to an early console
Rewrite the PDC console to become an early console, which can be used
for kgdb as well.
Signed-off-by: Helge Deller <deller@....de>
diff --git a/arch/parisc/include/asm/pdc.h b/arch/parisc/include/asm/pdc.h
index b643092d4b98..fcbcf9a96c11 100644
--- a/arch/parisc/include/asm/pdc.h
+++ b/arch/parisc/include/asm/pdc.h
@@ -19,9 +19,6 @@ extern unsigned long parisc_pat_pdc_cap; /* PDC capabilities (PAT) */
#define PDC_TYPE_SYSTEM_MAP 1 /* 32-bit, but supports PDC_SYSTEM_MAP */
#define PDC_TYPE_SNAKE 2 /* Doesn't support SYSTEM_MAP */
-void pdc_console_init(void); /* in pdc_console.c */
-void pdc_console_restart(void);
-
void setup_pdc(void); /* in inventory.c */
/* wrapper-functions from pdc.c */
diff --git a/arch/parisc/kernel/pdc_cons.c b/arch/parisc/kernel/pdc_cons.c
index 2661cdd256ae..45a4d2994857 100644
--- a/arch/parisc/kernel/pdc_cons.c
+++ b/arch/parisc/kernel/pdc_cons.c
@@ -1,46 +1,24 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
- * PDC Console support - ie use firmware to dump text via boot console
+ * PDC early console support - ie use firmware to dump text via boot console
*
- * Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
- * Copyright (C) 2000 Martin K Petersen <mkp at mkp.net>
- * Copyright (C) 2000 John Marvin <jsm at parisc-linux.org>
- * Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
- * Copyright (C) 2000 Philipp Rumpf <prumpf with tux.org>
- * Copyright (C) 2000 Michael Ang <mang with subcarrier.org>
- * Copyright (C) 2000 Grant Grundler <grundler with parisc-linux.org>
- * Copyright (C) 2001-2002 Ryan Bradetich <rbrad at parisc-linux.org>
- * Copyright (C) 2001 Helge Deller <deller at parisc-linux.org>
- * Copyright (C) 2001 Thomas Bogendoerfer <tsbogend at parisc-linux.org>
- * Copyright (C) 2002 Randolph Chung <tausq with parisc-linux.org>
- * Copyright (C) 2010 Guy Martin <gmsoft at tuxicoman.be>
+ * Copyright (C) 2001-2022 Helge Deller <deller@....de>
*/
/*
- * The PDC console is a simple console, which can be used for debugging
- * boot related problems on HP PA-RISC machines. It is also useful when no
- * other console works.
- *
* This code uses the ROM (=PDC) based functions to read and write characters
* from and to PDC's boot path.
*/
-/* Define EARLY_BOOTUP_DEBUG to debug kernel related boot problems.
- * On production kernels EARLY_BOOTUP_DEBUG should be undefined. */
-#define EARLY_BOOTUP_DEBUG
-
-
#include <linux/kernel.h>
#include <linux/console.h>
-#include <linux/string.h>
#include <linux/init.h>
-#include <linux/major.h>
-#include <linux/tty.h>
+#include <linux/serial_core.h>
+#include <linux/kgdb.h>
#include <asm/page.h> /* for PAGE0 */
#include <asm/pdc.h> /* for iodc_call() proto and friends */
static DEFINE_SPINLOCK(pdc_console_lock);
-static struct console pdc_cons;
static void pdc_console_write(struct console *co, const char *s, unsigned count)
{
@@ -54,210 +32,47 @@ static void pdc_console_write(struct console *co, const char *s, unsigned count)
spin_unlock_irqrestore(&pdc_console_lock, flags);
}
-int pdc_console_poll_key(struct console *co)
+static int kgdb_pdc_read_char(void)
{
- int c;
unsigned long flags;
+ int c;
spin_lock_irqsave(&pdc_console_lock, flags);
c = pdc_iodc_getc();
spin_unlock_irqrestore(&pdc_console_lock, flags);
- return c;
-}
-
-static int pdc_console_setup(struct console *co, char *options)
-{
- return 0;
-}
-
-#if defined(CONFIG_PDC_CONSOLE)
-#include <linux/vt_kern.h>
-#include <linux/tty_flip.h>
-
-#define PDC_CONS_POLL_DELAY (30 * HZ / 1000)
-
-static void pdc_console_poll(struct timer_list *unused);
-static DEFINE_TIMER(pdc_console_timer, pdc_console_poll);
-static struct tty_port tty_port;
-
-static int pdc_console_tty_open(struct tty_struct *tty, struct file *filp)
-{
- tty_port_tty_set(&tty_port, tty);
- mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);
-
- return 0;
-}
-
-static void pdc_console_tty_close(struct tty_struct *tty, struct file *filp)
-{
- if (tty->count == 1) {
- del_timer_sync(&pdc_console_timer);
- tty_port_tty_set(&tty_port, NULL);
- }
+ return (c <= 0) ? NO_POLL_CHAR : c;
}
-static int pdc_console_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
+static void kgdb_pdc_write_char(u8 chr)
{
- pdc_console_write(NULL, buf, count);
- return count;
+ if (PAGE0->mem_cons.cl_class != CL_DUPLEX)
+ pdc_console_write(NULL, &chr, 1);
}
-static unsigned int pdc_console_tty_write_room(struct tty_struct *tty)
-{
- return 32768; /* no limit, no buffer used */
-}
-
-static const struct tty_operations pdc_console_tty_ops = {
- .open = pdc_console_tty_open,
- .close = pdc_console_tty_close,
- .write = pdc_console_tty_write,
- .write_room = pdc_console_tty_write_room,
+static struct kgdb_io kgdb_pdc_io_ops = {
+ .name = "kgdb_pdc",
+ .read_char = kgdb_pdc_read_char,
+ .write_char = kgdb_pdc_write_char,
};
-static void pdc_console_poll(struct timer_list *unused)
-{
- int data, count = 0;
-
- while (1) {
- data = pdc_console_poll_key(NULL);
- if (data == -1)
- break;
- tty_insert_flip_char(&tty_port, data & 0xFF, TTY_NORMAL);
- count ++;
- }
-
- if (count)
- tty_flip_buffer_push(&tty_port);
-
- if (pdc_cons.flags & CON_ENABLED)
- mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);
-}
-
-static struct tty_driver *pdc_console_tty_driver;
-
-static int __init pdc_console_tty_driver_init(void)
-{
- struct tty_driver *driver;
- int err;
-
- /* Check if the console driver is still registered.
- * It is unregistered if the pdc console was not selected as the
- * primary console. */
-
- struct console *tmp;
-
- console_lock();
- for_each_console(tmp)
- if (tmp == &pdc_cons)
- break;
- console_unlock();
-
- if (!tmp) {
- printk(KERN_INFO "PDC console driver not registered anymore, not creating %s\n", pdc_cons.name);
- return -ENODEV;
- }
-
- printk(KERN_INFO "The PDC console driver is still registered, removing CON_BOOT flag\n");
- pdc_cons.flags &= ~CON_BOOT;
-
- driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW |
- TTY_DRIVER_RESET_TERMIOS);
- if (IS_ERR(driver))
- return PTR_ERR(driver);
-
- tty_port_init(&tty_port);
-
- driver->driver_name = "pdc_cons";
- driver->name = "ttyB";
- driver->major = MUX_MAJOR;
- driver->minor_start = 0;
- driver->type = TTY_DRIVER_TYPE_SYSTEM;
- driver->init_termios = tty_std_termios;
- tty_set_operations(driver, &pdc_console_tty_ops);
- tty_port_link_device(&tty_port, driver, 0);
-
- err = tty_register_driver(driver);
- if (err) {
- printk(KERN_ERR "Unable to register the PDC console TTY driver\n");
- tty_port_destroy(&tty_port);
- tty_driver_kref_put(driver);
- return err;
- }
-
- pdc_console_tty_driver = driver;
-
- return 0;
-}
-device_initcall(pdc_console_tty_driver_init);
-
-static struct tty_driver * pdc_console_device (struct console *c, int *index)
+static int __init pdc_earlycon_setup(struct earlycon_device *device,
+ const char *opt)
{
- *index = c->index;
- return pdc_console_tty_driver;
-}
-#else
-#define pdc_console_device NULL
-#endif
-
-static struct console pdc_cons = {
- .name = "ttyB",
- .write = pdc_console_write,
- .device = pdc_console_device,
- .setup = pdc_console_setup,
- .flags = CON_BOOT | CON_PRINTBUFFER,
- .index = -1,
-};
+ struct console *earlycon_console;
-static int pdc_console_initialized;
-
-static void pdc_console_init_force(void)
-{
- if (pdc_console_initialized)
- return;
- ++pdc_console_initialized;
-
/* If the console is duplex then copy the COUT parameters to CIN. */
if (PAGE0->mem_cons.cl_class == CL_DUPLEX)
memcpy(&PAGE0->mem_kbd, &PAGE0->mem_cons, sizeof(PAGE0->mem_cons));
- /* register the pdc console */
- register_console(&pdc_cons);
-}
-
-void __init pdc_console_init(void)
-{
-#if defined(EARLY_BOOTUP_DEBUG) || defined(CONFIG_PDC_CONSOLE)
- pdc_console_init_force();
-#endif
-#ifdef EARLY_BOOTUP_DEBUG
- printk(KERN_INFO "Initialized PDC Console for debugging.\n");
-#endif
-}
-
-
-/*
- * Used for emergencies. Currently only used if an HPMC occurs. If an
- * HPMC occurs, it is possible that the current console may not be
- * properly initialised after the PDC IO reset. This routine unregisters
- * all of the current consoles, reinitializes the pdc console and
- * registers it.
- */
-
-void pdc_console_restart(void)
-{
- struct console *console;
+ earlycon_console = device->con;
+ earlycon_console->write = pdc_console_write;
+ device->port.iotype = UPIO_MEM32BE;
- if (pdc_console_initialized)
- return;
+ if (IS_ENABLED(CONFIG_KGDB))
+ kgdb_register_io_module(&kgdb_pdc_io_ops);
- /* If we've already seen the output, don't bother to print it again */
- if (console_drivers != NULL)
- pdc_cons.flags &= ~CON_PRINTBUFFER;
-
- while ((console = console_drivers) != NULL)
- unregister_console(console_drivers);
-
- /* force registering the pdc console */
- pdc_console_init_force();
+ return 0;
}
+
+EARLYCON_DECLARE(pdc, pdc_earlycon_setup);
diff --git a/arch/parisc/kernel/setup.c b/arch/parisc/kernel/setup.c
index f005ddedb50e..375f38d6e1a4 100644
--- a/arch/parisc/kernel/setup.c
+++ b/arch/parisc/kernel/setup.c
@@ -70,6 +70,10 @@ void __init setup_cmdline(char **cmdline_p)
strlcat(p, "tty0", COMMAND_LINE_SIZE);
}
+ /* default to use early console */
+ if (!strstr(p, "earlycon"))
+ strlcat(p, " earlycon=pdc", COMMAND_LINE_SIZE);
+
#ifdef CONFIG_BLK_DEV_INITRD
if (boot_args[2] != 0) /* did palo pass us a ramdisk? */
{
@@ -139,8 +143,6 @@ void __init setup_arch(char **cmdline_p)
if (__pa((unsigned long) &_end) >= KERNEL_INITIAL_SIZE)
panic("KERNEL_INITIAL_ORDER too small!");
- pdc_console_init();
-
#ifdef CONFIG_64BIT
if(parisc_narrow_firmware) {
printk(KERN_INFO "Kernel is using PDC in 32-bit mode.\n");
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index b78f1b9d45c1..f9696fbf646c 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -239,13 +239,6 @@ void die_if_kernel(char *str, struct pt_regs *regs, long err)
/* unlock the pdc lock if necessary */
pdc_emergency_unlock();
- /* maybe the kernel hasn't booted very far yet and hasn't been able
- * to initialize the serial or STI console. In that case we should
- * re-enable the pdc console, so that the user will be able to
- * identify the problem. */
- if (!console_drivers)
- pdc_console_restart();
-
if (err)
printk(KERN_CRIT "%s (pid %d): %s (code %ld)\n",
current->comm, task_pid_nr(current), str, err);
@@ -429,10 +422,6 @@ void parisc_terminate(char *msg, struct pt_regs *regs, int code, unsigned long o
/* unlock the pdc lock if necessary */
pdc_emergency_unlock();
- /* restart pdc console if necessary */
- if (!console_drivers)
- pdc_console_restart();
-
/* Not all paths will gutter the processor... */
switch(code){
@@ -482,9 +471,7 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
unsigned long fault_space = 0;
int si_code;
- if (code == 1)
- pdc_console_restart(); /* switch back to pdc if HPMC */
- else if (!irqs_disabled_flags(regs->gr[0]))
+ if (!irqs_disabled_flags(regs->gr[0]))
local_irq_enable();
/* Security check:
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 877173907c53..898728ab2c18 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -602,21 +602,6 @@ config SERIAL_MUX_CONSOLE
select SERIAL_CORE_CONSOLE
default y
-config PDC_CONSOLE
- bool "PDC software console support"
- depends on PARISC && !SERIAL_MUX && VT
- help
- Saying Y here will enable the software based PDC console to be
- used as the system console. This is useful for machines in
- which the hardware based console has not been written yet. The
- following steps must be completed to use the PDC console:
-
- 1. create the device entry (mknod /dev/ttyB0 c 11 0)
- 2. Edit the /etc/inittab to start a getty listening on /dev/ttyB0
- 3. Add device ttyB0 to /etc/securetty (if you want to log on as
- root on this console.)
- 4. Change the kernel command console parameter to: console=ttyB0
-
config SERIAL_SUNSAB
tristate "Sun Siemens SAB82532 serial support"
depends on SPARC && PCI
diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
index 05dae05b6cc9..3b9a44008433 100644
--- a/lib/Kconfig.kgdb
+++ b/lib/Kconfig.kgdb
@@ -121,7 +121,7 @@ config KDB_DEFAULT_ENABLE
config KDB_KEYBOARD
bool "KGDB_KDB: keyboard as input device"
- depends on VT && KGDB_KDB
+ depends on VT && KGDB_KDB && !PARISC
default n
help
KDB can use a PS/2 type keyboard for an input device
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