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Message-id: <465DD753.5040208@sun.com>
Date: Wed, 30 May 2007 12:58:11 -0700
From: Yinghai Lu <Yinghai.Lu@....COM>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andi Kleen <ak@...e.de>, Russell King <rmk@....linux.org.uk>,
Bjorn Helgaas <bjorn.helgaas@...com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Gerd Hoffmann <kraxel@...e.de>,
David Gibson <david@...son.dropbear.id.au>
Subject: Re: [PATCH 4/5] serial: convert early_uart to earlycon for 8250
Andrew Morton wrote:
> On Tue, 29 May 2007 18:43:59 -0700
> Yinghai Lu <Yinghai.Lu@....COM> wrote:
>
>> [PATCH 4/5] serial: convert early_uart to earlycon for 8250
>>
>> Beacuse SERIAL_PORT_DFNS is removed from include/asm-i386/serial.h and
>> include/asm-x86_64/serial.h. the serial8250_ports need to be probed late
>> in serial initializing stage. the console_init=>serial8250_console_init=>
>> register_console=>serial8250_console_setup will return -ENDEV, and console
>> ttyS0 can not be enabled at that time.
>> need to wait till uart_add_one_port in drivers/serial/serial_core.c to call
>> register_console to get console ttyS0. that is too late.
>>
>> Make early_uart to use early_param, so uart console can be used earlier.
>> Make it to be bootconsole with CON_BOOT flag, so can use console handover
>> feature. and it will switch to corresponding normal serial console
>> automatically.
>>
>> new command line will be:
>> console=uart8250,io,0x3f8,9600n8
>> console=uart8250,mmio,0xff5e0000,115200n8
>> or
>> earlycon=uart8250,io,0x3f8,9600n8
>> earlycon=uart8250,mmio,0xff5e0000,115200n8
>>
>> it will print in very early stage:
>> Early serial console at I/O port 0x3f8 (options '9600n8')
>> console [uart0] enabled
>> later for console it will print:
>> console handover: boot [uart0] -> real [ttyS0]
>>
>>
>> Documentation/kernel-parameters.txt | 11 +++
>> arch/ia64/kernel/setup.c | 4 -
>> drivers/serial/8250.c | 28 ++-------
>> drivers/serial/8250_early.c | 104 ++++++++++++++----------------------
>> drivers/serial/Kconfig | 10 +++
>> include/asm-i386/fixmap.h | 2
>> include/asm-i386/io.h | 13 ++++
>> include/asm-ia64/io.h | 4 +
>> include/asm-x86_64/fixmap.h | 4 +
>> include/asm-x86_64/io.h | 13 ++++
>> include/linux/console.h | 2
>> include/linux/serial.h | 6 --
>> include/linux/serial_8250.h | 3 +
>> init/main.c | 5 +
>> kernel/printk.c | 22 +++++++
>> 15 files changed, 133 insertions(+), 98 deletions(-)
>
> This is a lot of tricky stuff in areas which I'm not very familar with.
> Need help, am not getting it.
>
>> @@ -143,12 +140,7 @@ static int __init parse_options(struct early_uart_device *device, char *options)
>> if (!strncmp(options, "mmio,", 5)) {
>> port->iotype = UPIO_MEM;
>> port->mapbase = simple_strtoul(options + 5, &options, 0);
>> - port->membase = ioremap(port->mapbase, mapsize);
>> - if (!port->membase) {
>> - printk(KERN_ERR "%s: Couldn't ioremap 0x%lx\n",
>> - __FUNCTION__, port->mapbase);
>> - return -ENOMEM;
>> - }
>> + port->membase = fix_ioremap(FIX_EARLYCON_MEM_BASE, port->mapbase);
>
> A number of useful-looking warnigns such as the above got removed. How come?
earycon, when you can not get fix_ioremap work, you can not get anything from boot.
>
>> mmio = 1;
>> } else if (!strncmp(options, "io,", 3)) {
>> port->iotype = UPIO_PORT;
>> @@ -175,9 +167,16 @@ static int __init parse_options(struct early_uart_device *device, char *options)
>> return 0;
>> }
>>
>> -static int __init early_uart_setup(struct console *console, char *options)
>> +static struct console early_serial8250_console __initdata = {
>> + .name = "uart",
>> + .write = early_serial8250_write,
>> + .flags = CON_PRINTBUFFER,
>
> Should this have CON_BOOT set as well?
>
> See
> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.21-rc7/2.6.21-rc7-mm2/broken-out/fixes-and-cleanups-for-earlyprintk-aka-boot-console.patch,
> which is now in mainline.
>
I put that into setup_early_serial8250_console.
-int __init early_serial_console_init(char *cmdline)
+static int __init setup_early_serial8250_console(char *cmdline)
{
char *options;
int err;
- options = strstr(cmdline, "console=uart,");
+ options = strstr(cmdline, "uart8250,");
if (!options)
- return -ENODEV;
+ return 0;
options = strchr(cmdline, ',') + 1;
- if ((err = early_uart_setup(NULL, options)) < 0)
+ if ((err = early_serial8250_setup(options)) < 0)
return err;
- return early_uart_console_init();
+
+ early_serial8250_console.flags |= CON_BOOT;
+ register_console(&early_serial8250_console);
+
+ return 0;
}
we may use
>> + .flags = CON_PRINTBUFFER | CAN_BOOT;
instead that line.
>> + .index = -1,
>> +};
>> +
>> +static int __init early_serial8250_setup(char *options)
>> {
>> - struct early_uart_device *device = &early_device;
>> + struct early_serial8250_device *device = &early_device;
>> int err;
>>
>> if (device->port.membase || device->port.iobase)
>> @@ -190,61 +189,40 @@ static int __init early_uart_setup(struct console *console, char *options)
>> return 0;
>> }
>>
>> -static struct console early_uart_console __initdata = {
>> - .name = "uart",
>> - .write = early_uart_write,
>> - .setup = early_uart_setup,
>> - .flags = CON_PRINTBUFFER,
>> - .index = -1,
>> -};
>
> hm, that didn't have CON_BOOT.
>
>> +static inline void __iomem * fix_ioremap (unsigned idx, unsigned long phys)
>
> I don't suppose it'd help much if I were to complain about the coding style
> (no space after the * or after the function name, please).
>
>> +{
>> + void __iomem * vaddr;
>> + set_fixmap_nocache(idx, phys & PAGE_MASK);
>> + vaddr = (void __iomem *)__fix_to_virt(idx);
>> + vaddr += phys & ~PAGE_MASK;
>> +
>> + return vaddr;
>> +}
>
> Probably this was a bit too large for inlining.
current only one calling, later will use that for usb debug cable.
>
>> /* Use early IO mappings for DMI because it's initialized early */
>> #define dmi_ioremap bt_ioremap
>> #define dmi_iounmap bt_iounmap
>> diff --git a/include/asm-ia64/io.h b/include/asm-ia64/io.h
>> index eb17a86..e29eaf8 100644
>> --- a/include/asm-ia64/io.h
>> +++ b/include/asm-ia64/io.h
>> @@ -423,6 +423,10 @@ extern void __iomem * ioremap(unsigned long offset, unsigned long size);
>> extern void __iomem * ioremap_nocache (unsigned long offset, unsigned long size);
>> extern void iounmap (volatile void __iomem *addr);
>>
>> +/* for console=uart8250,mmio,0xffe5000,9600n8 */
>> +#define FIX_EARLYCON_MEM_BASE 1
>> +#define fix_ioremap(idx, phys) ioremap(phys, 64)
>> +
>> /* Use normal IO mappings for DMI */
>> #define dmi_ioremap ioremap
>> #define dmi_iounmap(x,l) iounmap(x)
>
> So we touch ia64 as well?
>
>>
>> +int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
>> +{
>> + struct console_cmdline *c;
>> + int i;
>> +
>> + for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
>> + if (strcmp(console_cmdline[i].name, name) == 0 &&
>> + console_cmdline[i].index == idx) {
>> + c = &console_cmdline[i];
>> + memcpy(c->name, name_new, sizeof(c->name));
>> + c->name[sizeof(c->name) - 1] = 0;
>> + c->options = options;
>> + c->index = idx_new;
>> + return i;
>> + }
>> + /* not found */
>> + return -1;
>> +}
>
> Shouldn't this be __init?
>
> serial8250_find_port_for_earlycon() had its __init removed. Why?
with __init, the compiler will cry about .init.text and .text missection.
YH
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