On 10/19/21 18:12, Christophe Leroy wrote:
Le 19/10/2021 à 16:56, BALATON Zoltan a écrit :
On Tue, 19 Oct 2021, Christophe Leroy wrote:
Le 19/10/2021 à 15:44, Christophe Leroy a écrit :
There is something:
=> bootm 0
Wrong Image Format for bootm command
ERROR: can't get kernel image!
=> md 0
00000000: 00000000 b497aae1 616e9207 003227a4 '..V....an...2'.
00000010: 00000000 00000000 ee36255f 05070201 .........6%_....
00000020: 4c696e75 782d352e 31352e30 2d726335 Linux-5.15.0-rc5
00000030: 2d303232 32342d67 61336330 30376164 -02224-ga3c007ad
00000040: 1f8b0800 00000000 0203ec5c 0f7013e7 ...........\.p..
=> mw.l 0 0x27051956
=> bootm 0
## Booting kernel from Legacy Image at 00000000 ...
Image Name: Linux-5.15.0-rc5-02224-ga3c007ad
Image Type: PowerPC Linux Kernel Image (gzip compressed)
Data Size: 3286948 Bytes = 3.1 MiB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... Bad Data CRC
ERROR: can't get kernel image!
So we have something but it seems it gets overwritten by stuff.
Anyway loading a uImage at 0 is just bad because it is a gzipped image that
should get gunzipped at address 0.
Or should we just copy the raw kernel at 0 and jump to the entry point ? But
then we also need a device tree somewhere.
If I change KERNEL_LOAD_ADDR to 0x1000000, I can bootm at that address, and it
seems it properly decompress the kernel:
=> bootm 0x1000000
## Booting kernel from Legacy Image at 01000000 ...
Image Name: Linux-5.15.0-rc5-02224-ga3c007ad
Image Type: PowerPC Linux Kernel Image (gzip compressed)
Data Size: 3296789 Bytes = 3.1 MiB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
Uncompressing Kernel Image ... OK
And it initialises the MMU properly.
Then it gets stuck because there is no devicetree.
(gdb) bt
#0 0xc00094cc in udelay ()
#1 0xc0025d34 in panic ()
#2 0xc06415a0 in early_init_devtree ()
#3 0xc0641da8 in machine_init ()
#4 0xc0002200 in start_here ()
Maybe you need to embed a dtb in your kernel if that's possible somehow? Or QEMU
has a -dtb option that sets machine->dtb but you need board code to do
something with it. See how it's done in other boards like virtex_ml507 and
sam460ex. But maybe you'd be better off not using -kernel option as it seems to
not really working for these 405 boards but load and start the kernel from u-boot.
Not sure what device does u-boot support but QEMU can emulate usb-storage,
network, different disks so something might work with u-boot if this board has any
peripherals. If it doesn't emulate any peripherals what do you expect to do with
the kernel once it boots?
I should be able to build a multi-FIT image that embeds the kernel and the
device tree.
I don't know about the peripherals, what I need it a kernel that is able to
boot and run some user exe. I'm working on low level functionnalities like
VMAP_STACK, STRICT_KERNEL_RWX, Userspace protection, etc ... I want to be able
to check that after some modifications the kernel can still boot on every CPU
sub-family, and I need to run LKDTM tests.
For this a kernel + initrd is enough.
Thanks
Christophe
If we don't need a loader, we are better off simplifying the 405 boards with
a simple init sequence such as :
if (machine->kernel_filename) {
hwaddr kernel_base = 0;
int kernel_size = 0;
hwaddr initrd_base = 0;
int initrd_size = 0;
kernel_size = load_elf(machine->kernel_filename, NULL, NULL, NULL,
&boot_entry, &kernel_base, NULL, NULL,
0 /* LE */, PPC_ELF_MACHINE, 0, 0);
if (kernel_size < 0) {
error_report("Could not load kernel '%s' : %s",
machine->kernel_filename,
load_elf_strerror(kernel_size));
exit(1);
}
if (machine->initrd_filename) {
initrd_base = QEMU_ALIGN_UP(kernel_base + kernel_size, 0x10000);
initrd_size = load_image_targphys(machine->initrd_filename,
initrd_base, 16 * MiB /* Some
value */);
if (initrd_size < 0) {
error_report("Could not load initial ram disk '%s'",
machine->initrd_filename);
exit(1);
}
}
if (machine->dtb) {
dt_base = mw_dtb_load(machine, kernel_base, kernel_size,
initrd_base,
initrd_size);
}
}
We need to set the nip to 'boot_entry' and gpr[3] to 'dt_base'.
unless some pre-initialization of hw is required before running Linux ?
Thanks,
C.
