RE: kernel command-line size

[PEnright]

Just to be clear, I am trying to understand the limits on passing kernel
parameters. What version of Grub (old and/or new) or kernel do I need to
pass more information.

“Such whose distribution are you using, “Is this what you needed?
Linux version 2.6.28 (address@hidden) (gcc version 3.4.2
20041017 (Red Hat 3.4.2-6.fc3)) #1 SMP PREEMPT Sun Aug 31 01:41:53 CEST 2008

Below is where I was reading, but before I get to that let me see if I can
show you what my issue is.
Notice where the command line cuts off in the proc/comline.
My kernel parameters is:
pxe init=/linuxrc root=/dev/ram0 rw noapic nolapic lba devfs=nomount
ramdisk_size=33000 load_ramdis=1 promp_ramdisk=0 CIFS_Preferred=Y
Parts_To_Backup=sda1 Directory=\\10.77.77.30\PartImage passwd=PingAcess1
user=PartImageShare Server=10.77.77.30 Share=PartImage
Image_To_Restore=Create_New_Image New_Image_Name=JustSaved
Already_Existing_Image=Rename After_Completion=Shell Zsplit_Perferred=N
Minimize_Before_Storing=N Compression_Type=gzip
The proc/cmdline is:
pxe init=/linuxrc root=/dev/ram0 rw noapic nolapic lba devfs=nomount
ramdisk_size=33000 load_ramdis=1 promp_ramdisk=0 CIFS_Preferred=Y
Parts_To_Backup=sda1 Directory=\\10.77.77.30\PartImage passwd=PingAcess1
user=PartImageShare Server=10.77.77.30 Share=Pa


and of course where did you read this.  
According to http://kernelnewbies.org/Linux_2_6_21 says …
Dynamic kernel command-line

The current implementation stores a command-line buffer allocated to
COMMAND_LINE_SIZE (a compile-time constant) size - 256 bytes on x86. This is
not enough space today, some systems hit a limit when they use too many
module parameters, video settings, initramfs parameters etc. It's possible
to increase COMMAND_LINE_SIZE to a greater value, but there's a problem: a
static buffer of that size (say, 2KB) will be allocated even if you aren't
using all of it. 
So in 2.6.21 the size of the boot command line is allocated dynamically. A
static buffer is still allocated (2K in i386), but the contents are copied
into a dynamically-allocated buffer with the exact size, then the static
buffer is freed with the rest of the initdata data


Then http://lkml.indiana.edu/hypermail/linux/kernel/0501.2/1702.html says …
Boot loader version >= 0x0202 (which GRUB uses)
command line can be essentially any size, located anywhere in memory,
and the boot loader tells the kernel where to find it. The EDD real
mode code uses only this case for parsing the command line, and if an
older loader is used, EDD skips parsing the command line looking
for its options.



Gregg C Levine-2 wrote:
> 
> Hello!
> You'll have to be more specific. Such whose distribution are you using,
> and
> of course where did you read this.
> 
> Also that numbered release of the Legacy of GRUB is indeed old. It went to
> 0.97 before we actually decided to start expanding our horizons.
> 
> Beyond that, and without that information, we can't help you I am afraid.
> --
> Gregg C Levine address@hidden
> "The Force will be with you always." Obi-Wan Kenobi
>   
> 
> 
>> -----Original Message-----
>> From: address@hidden
> [mailto:bug-grub-
>> address@hidden On Behalf Of PEnright
>> Sent: Monday, February 23, 2009 2:41 PM
>> To: address@hidden
>> Subject: kernel command-line size
>> 
>> 
>> Not sure where to post this question, any help would be appreciated. If
> wrong
>> just tell where I can post.
>> 
>> I am not sure if this is a grub issue or kernel. I am using 2.6.28, grub
>> version 0.93. My command line parameters (kernel) is being truncated at
> 256
>> characters. I read one thing that says since 2.6.21 the linux kernel is
>> dynamic. This makes me think it is a grub issue. Am I using the wrong
>> version? Would version 2 fix this? Can I get a binary version for the
>> i386
>> pc?
>> 
>> 
>> --
>> View this message in context:
> http://www.nabble.com/kernel-command-line-size-
>> tp22168505p22168505.html
>> Sent from the Grub - Bugs mailing list archive at Nabble.com.
>> 
> 
> 

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