Messages in this thread Patch in this message | | | From | Jason Cox <> | Subject | Re: Change number of tty devices | Date | Thu, 22 Apr 2004 03:15:16 +0000 |
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On Wed, 21 Apr 2004 21:14:38 +0100 (BST) James Simmons <jsimmons@infradead.org> wrote:
> > > Often, I have wondered what the need for 64 tty devices in /dev is. > > I began tinkering with the code and am wondering why it's not user > > configurable. I came up with a quick patch to add it as an option > > under drivers/char/Kconfig. I also made a lower bound of 12. If this > > is an idea worth pursuing, please let me know. If this idea has been > > rejected before, I apologize. What do you think of this idea? > > The reason for 64 is that the major number is shared between the > serial tty and VT tty drivers. The first 64 to Vts and the rest to > serial devices. What is even more is that athere exist ioctls that > return shorts which means only 16 VCs can be accounted for on a VT. > When the kernel supports multi-desktop systems we will have to deal > with the serial and VT issue. Most likely the serial tty drivers will > be given a different major number. I personally believe that because > of the 16 bit limit that there should be 16 VCs per VT terminal.
Ok, I made a new patch where the upper limit is set to 63. It is there anything wrong with doing this per se?
diff -urN linux-2.6.5/drivers/char/Kconfig linux-2.6.5-work/drivers/char/Kconfig --- linux-2.6.5/drivers/char/Kconfig 2004-04-03 21:36:15.000000000 -0600 +++ linux-2.6.5-work/drivers/char/Kconfig 2004-04-21 22:04:11.647195120 -0500 @@ -57,6 +57,18 @@ If unsure, say Y. +config NR_TTY_DEVICES + int "Maximum tty device number" + depends on VT + default 63 + ---help--- + This is the highest numbered device created in /dev. You will actually have + NR_TTY_DEVICES+1 devices in /dev. The default is 63, which will result in + 64 /dev entries. The lowest number you can set is 11, anything below that, + and it will default to 11. 63 is also the upper limit so we don't overrun + the serial consoles. + + config HW_CONSOLE bool depends on VT && !S390 && !UM diff -urN linux-2.6.5/include/linux/tty.h linux-2.6.5-work/include/linux/tty.h --- linux-2.6.5/include/linux/tty.h 2004-04-03 21:37:07.000000000 -0600 +++ linux-2.6.5-work/include/linux/tty.h 2004-04-21 22:06:18.000000000 -0500 @@ -10,8 +10,19 @@ * resizing). */ #define MIN_NR_CONSOLES 1 /* must be at least 1 */ -#define MAX_NR_CONSOLES 63 /* serial lines start at 64 */ -#define MAX_NR_USER_CONSOLES 63 /* must be root to allocate above this */ +#if (CONFIG_NR_TTY_DEVICES < 11) +/* Lower Limit */ +#define MAX_NR_CONSOLES 11 +#define MAX_NR_USER_CONSOLES 11 +#elseif (CONFIG_NR_TTY_DEVICES > 63) +/* Upper Limit */ +#define MAX_NR_CONSOLES 63 +#define MAX_NR_USER_CONSOLES 63 +#else +/* They chose a sensible number */ +#define MAX_NR_CONSOLES CONFIG_NR_TTY_DEVICES +#define MAX_NR_USER_CONSOLES CONFIG_NR_TTY_DEVICES +#endif /* Note: the ioctl VT_GETSTATE does not work for consoles 16 and higher (since it returns a short) */
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