Re: [OpenBIOS] [Qemu-devel] OpenBios in Sparc can't handle long kernel command lines.

[Mark Cave-Ayland]

On 22/03/13 05:19, Rob Landley wrote:
> If I do this:
>
> qemu-system-sparc -nographic -no-reboot -kernel image -hda hda.sqf
> -append 'root=/dev/sda rw init=/sbin/init.sh panic=1
> PATH=/usr/distcc:/bin:/sbin console=ttyS0 HOST=sparc CPUS=1
> DISTCC_HOSTS=10.0.2.2:31322/1 FTP_SERVER=10.0.2.2 FTP_PORT=31307
> NATIVE_BUILD=lfs-bootstrap ' -hdb hdb.img -hdc lfs-bootstrap.hdc -m 256
>
> qemu goes:
>
> ^[[H^[[JConfiguration device id QEMU version 1 machine id 32
> CPUs: 1 x FMI,MB86904
> Unhandled Exception 0x00000007
> PC = 0xffd07d28 NPC = 0xffd07d2c
> Stopping execution
>
> And then hangs. I've never figured out why it clears the screen first
> (none of the other targets do), but I _have_ figured out that the
> unhandled exception is "kernel command line too long". Because 197 bytes
> is just too much data for Sparc to cope with.

This is actually a bug in OpenBIOS which declares the command line 
storage like this:

static void
arch_init( void )
{
         static char cmdline[128];

....

kernel_cmdline = (const char *) 
fw_cfg_read_i32(FW_CFG_KERNEL_CMDLINE);
         if (kernel_cmdline) {
             size = strlen(kernel_cmdline);
             memcpy(cmdline, kernel_cmdline, size);
             obp_arg.argv[1] = cmdline;
         }
         cmdline[size] = '\0';

....
}

Would increasing it to 256 bytes be enough? I can't say I've ever come 
across command lines in a normal environment with more than about 80 
characters, but I don't see an issue with increasing it.

ATB,

Mark.

[Qemu-devel] OpenBios in Sparc can't handle long kernel command lines.

[Blue Swirl]

On Thu, Mar 28, 2013 at 7:20 PM, Mark Cave-Ayland
 wrote:
> On 22/03/13 05:19, Rob Landley wrote:
> > If I do this:
> >
> > qemu-system-sparc -nographic -no-reboot -kernel image -hda hda.sqf
> > -append 'root=/dev/sda rw init=/sbin/init.sh panic=1
> > PATH=/usr/distcc:/bin:/sbin console=ttyS0 HOST=sparc CPUS=1
> > DISTCC_HOSTS=10.0.2.2:31322/1 FTP_SERVER=10.0.2.2 FTP_PORT=31307
> > NATIVE_BUILD=lfs-bootstrap ' -hdb hdb.img -hdc lfs-bootstrap.hdc -m 256
> >
> > qemu goes:
> >
> > ^[[H^[[JConfiguration device id QEMU version 1 machine id 32
> > CPUs: 1 x FMI,MB86904
> > Unhandled Exception 0x00000007
> > PC = 0xffd07d28 NPC = 0xffd07d2c
> > Stopping execution
> >
> > And then hangs. I've never figured out why it clears the screen first
> > (none of the other targets do), but I _have_ figured out that the
> > unhandled exception is "kernel command line too long". Because 197 bytes
> > is just too much data for Sparc to cope with.
>
> This is actually a bug in OpenBIOS which declares the command line storage
> like this:
>
> static void
> arch_init( void )
> {
>         static char cmdline[128];
>     ....
>
>     kernel_cmdline = (const char *)
>
> fw_cfg_read_i32(FW_CFG_KERNEL_CMDLINE);
>         if (kernel_cmdline) {
>             size = strlen(kernel_cmdline);
>             memcpy(cmdline, kernel_cmdline, size);
>             obp_arg.argv[1] = cmdline;
>         }
>         cmdline[size] = '\0';
>     ....
>
> }
>
> Would increasing it to 256 bytes be enough? I can't say I've ever come
> across command lines in a normal environment with more than about 80
> characters, but I don't see an issue with increasing it.

Isn't strdup() (or memory allocation subsystem) available at that time?
> ATB,
>
> Mark.

[Qemu-devel] OpenBios in Sparc can't handle long kernel command lines.

[Tarl Neustaedter]

On 2013-Mar-28 15:20 , Mark Cave-Ayland wrote:
> [ command line limited to 80 bytes ]
> Would increasing it to 256 bytes be enough? I can't say I've ever come 
> across command lines in a normal environment with more than about 80 
> characters, but I don't see an issue with increasing it.

In openboot, we run into long command lines primarily when we do network 
boot - the arguments to network devices (particularly for things like 
iSCSI) can get absurdly long.

E.g.

ok boot 
/pci@340/pci@1/pci@0/network@5:iscsi-target-ip=179.182.226.103,iscsi-target-name=iqn.1986-03.com.sun:02:boot,host-ip=182.179.226.205,iscsi-port=3260,iscsi-lun=1,iscsi-partition=a,router-ip=182.179.226.254,subnet-mask=255.255.255.0

The above has an unusually short iscsi-target-name. Many iqn strings go 
over 80 bytes by themselves.