A new port of uClinux on PSP (with accessibility to ms0)

[vijay]

thanx alot riverful ..... :) finally got installed the toolchain oof .... :)

and roge upgrade to 4.2.1 ........... i solves many prob ........ i also used to get arbit error on 4.1 gcc

[roge]

yep vijay, i have success on gcc 4.2

finally.. :D

thanks riverful, jackson

now to kernel!

[vijay]

while applying the kernel patch, it asked me about linking to the following files

Code: Select all

arch/mips/psp/ipl_sdk/sysreg.c
arch/mips/psp/ipl_sdk/syscon.c
arch/mips/psp/ipl_sdk/memstk.c
arch/mips/psp/ipl_sdk/psp_uart.c 

so i downloaded ipl_sdk from net and kept in the appropriate place ....... and i applied the patch

now when compiling the kernel using

Code: Select all

 make ARCH=mips CROSS_COMPILE=mipsel-linux- vmlinux.bin

im getting these error messages

Code: Select all

  CC      arch/mips/psp/ipl_sdk/memstk.o
arch/mips/psp/ipl_sdk/memstk.c:8:23: error: pspkernel.h: No such file or directory
arch/mips/psp/ipl_sdk/memstk.c:9:21: error: Kprintf.h: No such file or directory
In file included from arch/mips/psp/ipl_sdk/memstk.c:11:
arch/mips/psp/ipl_sdk/syscon.h:88: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:90: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'Syscon_wait'
arch/mips/psp/ipl_sdk/syscon.h:92: error: expected ')' before 'cmd'
arch/mips/psp/ipl_sdk/syscon.h:93: error: expected ')' before 'param'
arch/mips/psp/ipl_sdk/syscon.h:94: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h: In function 'pspSysconNop':
arch/mips/psp/ipl_sdk/syscon.h:101: warning: implicit declaration of function 'pspSyscon_tx_noparam'
arch/mips/psp/ipl_sdk/syscon.h: At top level:
arch/mips/psp/ipl_sdk/syscon.h:102: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:103: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:104: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:106: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:107: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:109: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:110: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:111: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:112: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:114: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:115: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:117: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:122: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:124: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:131: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:132: error: expected ')' before 'sw'
arch/mips/psp/ipl_sdk/syscon.h:133: error: expected ')' before 'sw'
arch/mips/psp/ipl_sdk/syscon.h:137: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:138: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:139: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:140: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:141: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:143: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:144: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:145: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:146: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:147: error: expected ')' before 'sw'
arch/mips/psp/ipl_sdk/syscon.h:148: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:153: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:160: error: expected ')' before 'val'
arch/mips/psp/ipl_sdk/syscon.h:161: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:162: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:163: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:164: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:165: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:166: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:167: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:168: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:169: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:170: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:171: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:172: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:173: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:174: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:175: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:176: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:177: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/syscon.h:178: error: expected ')' before '*' token
arch/mips/psp/ipl_sdk/memstk.c: In function 'ms_check_status':
arch/mips/psp/ipl_sdk/memstk.c:184: error: 'u8' undeclared (first use in this function)
arch/mips/psp/ipl_sdk/memstk.c:184: error: (Each undeclared identifier is reported only once
arch/mips/psp/ipl_sdk/memstk.c:184: error: for each function it appears in.)
arch/mips/psp/ipl_sdk/memstk.c:184: error: expected ';' before 'sts'
arch/mips/psp/ipl_sdk/memstk.c:197: error: 'sts' undeclared (first use in this function)
make[1]: *** [arch/mips/psp/ipl_sdk/memstk.o] Error 1
make: *** [arch/mips/psp] Error 2
vijay@vijay-desktop:/usr/src/uclinux$ 

[roge]

vijay, install pspsdk and psptoolchain from p2dev.org
if you have already installed on your machine, edit kernel.config, find the variable of pspsdk and make it correct.

-----------------


i get some erros on compile kernel, but its about sdk.. resolved!

i compile buildroot and kernel..
i have an uclinux.bin with 1.4mb (ctypes??) whatever..

when i test on my psp (3.71 m33-4) (jackson bootloader)
my psp brake on loading..

decompressing linux kernel....1416422 bytes loaded
transfering control to 0x80000000...

whats it jackson?

[vijay]

i changed the paths in .config file
CONFIG_PSP_SDK_PATH="/usr/local/pspdev/psp/sdk"
CONFIG_PSP_TOOLCHAIN_PATH="/usr/local/pspdev/psp"

the errors got solved .... and i got a vmlinux around 1.6mb file after compiling
like roge said mine too, shows till
decompressing linux kernel....1612342 bytes loaded
and then my psp shutsdown

[riverful]

hi vijay & roge!

perhaps, this problem is cause of gzip compress.

1. make vmlinux.bin ( perhaps 1.6mb )
2. # gzip -9 arch/mips/boot/vmlinux.bin
3. # ls -al arch/mips/boot/vmlinux.bin.gz
4. rename this file to vmlinux.bin, then use this. :)

according to jackson's page,
the bootloader made by jackson, supports gzip compress.
in the source of bootloader, gzip function is used.

ps. hey roge~ my nickname is riverful, not hiverful!! haha :)

[M.Jackson]

Hey guys, i had no idea it could create so much drama on applying the kernel patch. Perphas the previous patch for new files (like the ones from the IPL SDK) was not properly generated hence it does not contain all the content you need for compiling the kernel. I have uploaded a new kernel patch to my website and please have a try. If you still run into any compilation problem for the kernel please let me know.

[roge]

Sorry riverful.. :)

I try to gzip vmlinux.bin and the same error.. brake psp on boot! :(

i will make clean on kernel and apply new jackson patch.

lucky for us:D

[vijay]

hi jackson i tried with the new patch but having the same problem

[M.Jackson]

hi jackson i tried with the new patch but having the same problem

You mean you are still getting the same compilation problem? or keep getting your psp shutdown during kernel booting? If it is the latter, did you try to boot it under the 1.5 firmware?

[vijay]

its the later one .......... no i haven't tested it on 1.5 firmware as i have only psp slim (3.71 m33-4)

[jmfriedt]

After sucessfully compiling all toolchains, I can get a working vmlinux.bin kernel
which boots fine, but busybox will crash with a dump of all register values after
the kernel frees memory. I tried with the busybox provided by Jackson (after
extracting it from his vmlinux.bin image and including it in my own rootfs) or from
the one I compile with the resulting toolchain. Has anyone got to the point of getting a
shell from his own toolchain compilation ?
Furthermore, I am surpried by the lack of /dev/ttySRC2 in both Jackson's image and
riverful tutorials: how do you agetty /dev/ttySRC2 running without this /dev entry ?
My objective is to get a terminal in minicom since entering command through the
virtual on-screen keyboard is ... inconvenient to say the least.

[M.Jackson]

After sucessfully compiling all toolchains, I can get a working vmlinux.bin kernel
which boots fine, but busybox will crash with a dump of all register values after
the kernel frees memory. I tried with the busybox provided by Jackson (after
extracting it from his vmlinux.bin image and including it in my own rootfs) or from
the one I compile with the resulting toolchain. Has anyone got to the point of getting a
shell from his own toolchain compilation ?
Furthermore, I am surpried by the lack of /dev/ttySRC2 in both Jackson's image and
riverful tutorials: how do you agetty /dev/ttySRC2 running without this /dev entry ?
My objective is to get a terminal in minicom since entering command through the
virtual on-screen keyboard is ... inconvenient to say the least.

Glad to know you can boot up the kernel built by the new toolchain. Did you boot it under the 1.5 firmware or the 3.xx?

As to busybox, I did mention in my site that the new kernel built by the new toolchain is NOT binary compatible with the any old executables made by the old toolchain, due to a minor change in argument passing. And so it is for the old kernel and the new executables. Therefore it is not surprised to see your busybox extracted from the old image did not work.

And for the stuff under /dev, you have got to create them yourself :) Just typing a few mknod commands will do all the magic. And it is absolutely possible to run a terminal via minicom as I am doing it all the time. I am even thinking to make some changes in inittab to enable switching between serial and virtual terminals on demand.

[jmfriedt]

Glad to know you can boot up the kernel built by the new toolchain. Did you boot it under the 1.5 firmware or the 3.xx?

I work on an old model PSP running the 1.5 firmware. Since I am not familiar with the
various homebrew formats, I was unable to run the binary bootloader you provide on your
website but successfully compiled from source to generate the two directories
(pspboot and pspboot%) I am familiar with during my own developments.

As to busybox, I did mention in my site that the new kernel built by the new toolchain is NOT binary compatible with the any old executables made by the old toolchain, due to a minor change in argument passing. And so it is for the old kernel and the new executables. Therefore it is not surprised to see your busybox extracted from the old image did not work.

Good. I thought that issue was solved, but at least this result is expected. What
direction should we look into to try and solve this issue ?

And for the stuff under /dev, you have got to create them yourself :) Just typing a few mknod commands will do all the magic. And it is absolutely possible to run a terminal via minicom as I am doing it all the time. I am even thinking to make some changes in inittab to enable switching between serial and virtual terminals on demand.

So I did, I was just surprised it was not done in the default image. Indeed enabling
getty in the inittab would be very nice. This really is my first objective.

[riverful]

hey jmfreidt~!

after u make install busybox, u must mknod serial node.
the method is following.

# make install
# cd _install ( in the busybox dir )
# ls
bin sbin usr
# mkdir dev etc ms0 proc usr var
# mknod dev/ttySRC c 4 202

ttySRC is charactor device ( serial ) and has MAJOR 4, MINOR 202.
it's cause of that.

in kernel_dir/drivers/serial/serial_psp.c

Code: Select all

 41 /*-----------------------------------------------------------------------------
 42  * Constants
 43  *---------------------------------------------------------------------------*/
 44 #define PSP_SERIAL_NAME         "ttySRC"
 45 #define PSP_SERIAL_MAJOR        4
 46 #define PSP_SERIAL_MINOR        200
 47 #define PSP_SERIAL_NUM_PORTS    3

ttySRC's MINOR number starts 200. so, i think that ttySRC2's minor number is 202.

my inittab example is following.

Code: Select all

# /etc/inittab

::once:mount -t proc proc /proc
::once:mount -t vfat /dev/ms0 /ms0

#::respwan:-/bin/msh

ttySRC2::respawn:-/bin/sh
#tty1::askfirst:-/bin/msh
#tty1::respawn:-/bin/msh
#tty2::respawn:-/bin/msh
#tty3::respawn:-/bin/msh
#tty4::respawn:-/bin/msh
#tty5::respawn:-/bin/msh
#tty6::respawn:-/bin/msh

::shutdown:/bin/umount -a -r

i don't use agetty. and, i just need shell command prompt.
because i commented tty1~6 line, i don't see messsage on the PSP lcd.
if u wanna see message and command on the PSP lcd,
u must uncomment tty1~6 line.

my "stty -a" is following.

Code: Select all

:/> stty -a

speed 0 baud; rows 24; columns 80;
intr = <undef>; quit = <undef>; erase = <undef>; kill = <undef>; eof = <undef>;
eol = <undef>; eol2 = <undef>; swtch = M-@; start = P; stop = &#58;; susp = M-^I;
rprnt = <undef>; werase = <undef>; lnext = U; flush = <undef>;
min = 0; time = 0;
-parenb -parodd cs5 -hupcl -cstopb -cread -clocal -crtscts
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon
-ixoff -iuclc -ixany -imaxbel
-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0
ff0
-isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop
-echoprt -echoctl -echoke

i hope to help u. :D[/code]

[M.Jackson]

I have released a new bootloader v0.22 capbable of running on 2.0+ firmware and slim PSP (in theory). Besides a few bug fixing, the major change in this version is employing a safer way of running code in the kernel mode avoiding the risk of overwriting the in-used code during RAM transfer. It has been tested on 3.71 m33-4 on my psp (I just upgraded it last night to get the closest testing environment to slim) and has not yet been tested on slim. But theoretically it should work just the same. Can anybody help to test it?

The prebuilt package can be downloaded here: http://myfreefilehosting.com/f/960525c96b_0.09MB

Thanks

[cloudhunter]

I have released a new bootloader v0.22 capbable of running on 2.0+ firmware and slim PSP (in theory). Besides a few bug fixing, the major change in this version is employing a safer way of running code in the kernel mode avoiding the risk of overwriting the in-used code during RAM transfer. It has been tested on 3.71 m33-4 on my psp (I just upgraded it last night to get the closest testing environment to slim) and has not yet been tested on slim. But theoretically it should work just the same. Can anybody help to test it?

The prebuilt package can be downloaded here: http://myfreefilehosting.com/f/960525c96b_0.09MB

Thanks

Didn't danzel already port it? Nevertheless, good work. Is there any chance of getting the Linux Kernel to support the extra 32 MB available on the Slim?

Cloudy

[M.Jackson]

Didn't danzel already port it? Nevertheless, good work. Is there any chance of getting the Linux Kernel to support the extra 32 MB available on the Slim?

Cloudy

I just change the way of entering the kernel mode which should reduce the possibility of crash since the location where a prx is loaded is kind of unpredictable and if the kernel gets larger in future there is a greater chance that the prx may overwrite itself in RAM during kernel transfer. By this new design, even if the prx gets overwritten it won't hamper the kernel booting at all. But off course all these details are transparent to users and the most important thing is it just work.

For utilizing the extra 32MB on slim, it should be quite possible if the extra 32MB can be accessed directly just like the lower 32MB (within the same linear address space without any special protection or weird way of mem mapping).

[sivaji]

hi!

i Have a psp dlim & light, so where can i get the kernel package ?



ps: sorry for my bad english because i'm french

[sim]

Hello,

I have done a set of patches against the buildroot (snapshot 20071216).
They are available at http://www.sequanux.org/sim/PSP/buildro ... p-patches/.

They add busybox, psposk, initramfs and kernel build in the buildroot framework.
Buildroot will not only build the toolchain but the target vmlinux.bin image too.

A buildroot configuration is available at http://www.sequanux.org/sim/PSP/buildro ... psp.config

Once the patches are applied (in the right order) and the default configuration rename in .config... just execute the command "make oldconfig; make".

After the compilation, the resulting image can be found at ./project_build_mipsel/linuxonpsp/linux-2.6.22/arch/mips/boot/vmlinux.bin.

Before performing the flash operation, the vmlinux.bin file must gziped...

ps: serial login don't work properly with the resulting image... must be fixed :)

[J.F.]

For utilizing the extra 32MB on slim, it should be quite possible if the extra 32MB can be accessed directly just like the lower 32MB (within the same linear address space without any special protection or weird way of mem mapping).

The slim memory is one single block of 64M starting at the same place as the 32M on the phat. All you have to do to use the extra memory is make the size/end 32M bigger and it should start using the extra memory.

[jmfriedt]

To further develop on sim's post (since I had the opportunity of debugging his
installation procedure), the purpose of this set of patches was to fully use the
feature of buildroot to use the appropriate busybox + kernel in a unified
environment. So sim generated the 6 patches available at the url he provided: these
patches are to be applied sequentially to the 20071216 buidroot archive.
After applying these patches, and using his configure file,
make oldconfig && make
will generate project_build_mipsel/linuxonpsp/linux-2.6.22/arch/mips/boot/vmlinux.bin
This image, after compressing (gzip -9) and renaming vmlinux.bin, is the one ready
for use by Jackson's bootloader (tested on PSP fat, firmware 1.5).
The rootfs filesystem is available in project_build_mipsel/linuxonpsp/root: any manual
change to this rootfs in included in a new vmlinux.bin by rm initramfs.cpio.gz in
project_build_mipsel/linuxonpsp/linux-2.6.22/usr/ followed by
make linux26 from buildroot directory.

ps: serial login don't work properly with the resulting image... must be fixed :)

Actually "don't work properly" is not right, let's say the serial port is behaving awkwardly:
any command typed on the serial port (115200 baud, N81) is echoed on the LCD (tty1 ?),
and while the result of the command appears on the LCD, the terminal connected to the
serial port echoes a "login" prompt instead of the result. Nice behaviour but quite unexpected.

[Rammsteinfan13]

how can I get back to the XMB on a slim. I got it worked with Mo's bootloader thnx. And is it possible to run a GUI on it?

[cloudhunter]

how can I get back to the XMB on a slim. I got it worked with Mo's bootloader thnx. And is it possible to run a GUI on it?

You type poweroff to turn it off... Then turn the PSP on, and you get back to the XMB ;)

M.Jackson: Thanks for the explanation - forgot about the differences between static elf's and prx's.

Cloudy

[M.Jackson]

...
Actually "don't work properly" is not right, let's say the serial port is behaving awkwardly:
any command typed on the serial port (115200 baud, N81) is echoed on the LCD (tty1 ?),
and while the result of the command appears on the LCD, the terminal connected to the
serial port echoes a "login" prompt instead of the result. Nice behaviour but quite unexpected.

In fact, instead of being unexpected this has been designed on purpose and probably requires no fixing :) If you take a look at the serial driver (serial_psp.c) you will see whenever the driver takes a char from the serial port, it passes it to both the serial console (SIO) and the active virtual console (ttyx) if they are enabled in kernel compile. I made it this way because I wanted to use my PC as a keyboard for typing commands even if I was using virtual terminals on the LCD. If you wanna do away with the virtual consoles and to work purely on serial, just turn off all vt related options and make sure "SIO console on psp" is enabled in kernel config, change /etc/inittab to launch the shell on "console" device, and tie console to ttySRC2 at boot command to make it happen.

Actually it doesn't quite make sense to "login" to the psp before using the shell 'cos it is not like you can have multiple users working on it simultaneously for the time being. Or can you?

[jmfriedt]

In fact, instead of being unexpected this has been designed on purpose and probably requires no fixing :)

excellent, since I wanted to make a PS2 keyboard to RS232 converter (already available as an example for mspgcc) but was wondering how to echo the characters I type: your implementation of ttySRC2 answers my needs.

[jmfriedt]

Actually it doesn't quite make sense to "login" to the psp before using the shell 'cos it is not like you can have multiple users working on it simultaneously for the time being. Or can you?

not yet, not yet ...

Another question, since the kbd echo on terminal works nicely (and I now understand
why you didn't have ttySRC2 in inittab): is the ms0 supposed to work on PSP fat ?
I get
PSP Memory Stick block device (NEW)
PSP MemoryStick: failed to read sector 0, err=-1
PSP MemoryStick: failed to read MBR, err=-1
on a 32 MB MS.
I have not checked the source code, just wondering ...

[vijay]

at last i got a running kernel
-------------------
i think the problem is , before when im compiling the kernel it asked something about openswan , so i downloaded the openswan source and kept in appropriate places ...... and compiled kernel

but this time i just commented out the openswan line in Kconfig and now im able to boot
--------------------
but the problem is it stops by saying

PSP: Joypad driver (NEW)
VFS: Cannot open root device "<NULL>" or unknow-block(0,0)
Please append a correct "root=" boot option; here are the availble partitions: 1fc8 3964920 ms0 <driver?>
------------------------------------------
and i compiled the psposk driver .... how to make it start when kernel boots????

[M.Jackson]

Actually it doesn't quite make sense to "login" to the psp before using the shell 'cos it is not like you can have multiple users working on it simultaneously for the time being. Or can you?

not yet, not yet ...

Another question, since the kbd echo on terminal works nicely (and I now understand
why you didn't have ttySRC2 in inittab): is the ms0 supposed to work on PSP fat ?
I get
PSP Memory Stick block device (NEW)
PSP MemoryStick: failed to read sector 0, err=-1
PSP MemoryStick: failed to read MBR, err=-1
on a 32 MB MS.
I have not checked the source code, just wondering ...

Unfortunately, the driver is only compatible with the MS PRO series (mine is MS duo pro with 4GB capacity) as the low-level IPL driver it depends on seems designed for PRO only. Your 32MB MS is probably not one of the PRO variants, is it?

[M.Jackson]

at last i got a running kernel
-------------------
i think the problem is , before when im compiling the kernel it asked something about openswan , so i downloaded the openswan source and kept in appropriate places ...... and compiled kernel

but this time i just commented out the openswan line in Kconfig and now im able to boot
--------------------
but the problem is it stops by saying

PSP: Joypad driver (NEW)
VFS: Cannot open root device "<NULL>" or unknow-block(0,0)
Please append a correct "root=" boot option; here are the availble partitions: 1fc8 3964920 ms0 <driver?>
------------------------------------------
and i compiled the psposk driver .... how to make it start when kernel boots????

This is typical: you forgot to mount a root device when booting, and it should have nothing to do with the joypad driver or osk. There are two ways of doing it:

a) Build a root file system on your pc (the directory structure that contains /dev/*, /etc/*, busybox and all other usual but necessary stuff. Just check out my pre-built version to find out what you are gonna need) and pack it with cpio. And then specify the cpio package in General Setup->Initramfs source in kernel config before recompiling the kernel. Or,

b) Build the same root fs on the root of ms0 and add root=/dev/ms0 to boot command in pspboot.conf. I didn't try this but it should work.

If you are not familiar with initramfs just google it. There are tons of tutorials available on the net.