Error while cross compiling linux kernel

[knilaks...@gmail.com]

based on the instructions given in https://github.com/riscv/riscv-tools/tree/new_privileged_isa

I tried to cross compile Linux 4.18.14 kernel.Itried the command  make -j ARCH=riscv

but got some unreference error.ThenI tried  make -j ARCH=riscv CROSS_COMPILE=
risc64-unknown-linux-gnu-

I got the follwing error


Makefile:1027: recipe for target 'vmlinux' failed
arch/riscv/kernel/setup.o: In function `.L24':
setup.c:(.init.text+0x2e2): undefined reference to `swiotlb_init'
Makefile:1027: recipe for target 'vmlinux' failed
make: *** [vmlinux] Error 1




Any suggestions to overcome this?





[Michael Clark]

Try this patch (apply with patch -p1 < swiotlb.patch)

https://gist.github.com/michaeljclark/a02ba9361805125538ce09ebbadae89e

[knilaks...@gmail.com]

Thanks Michael it working.

I have some more confusion

1.How can I edit the configuration to support MMU less architecture for 32 bit RISCV?

2.When executing curl http://www.ocf.berkeley.edu/~qmn/linux/linux-inittab > etc/inittab   I got permission error bash: etc/inittab: Permission denied

Its denied even when I used the sudo command.Any suggestions ?

thanks

[Michael Clark]

On 19/10/2018, at 10:40 PM, knilaks...@gmail.com wrote:

Thanks Michael it working.

I have some more confusion

1.How can I edit the configuration to support MMU less architecture for 32 bit RISCV?

There is no no-MMU Linux port at present. The port requires FDPIC support in binutils. In regular PIC binaries, the offset between the read-only .text,.rodata sections and the read-write .data,.bss sections is fixed. This is historical. No-MMU systems require multiple instances of the same binary or shlib to be shared with the same addresses for .text,.rodata and different memory addresses for .data,.bss. 

In FDPIC, the offset to .data,.bss is no longer PC-Relative like it is with PIC rather it is relative to a TOC register, likely gp-relative on RISC-V as gp is currently reserved when generating PIC code. FDPIC also requires function pointers to point to function descriptors that contain both the function address and the FDPIC register value (pointer to GOT Base in .data,.bss). The FDPIC register needs to be loaded in the PLTs for inter-module calls, so each module can find its .data,.bss (as it’s no longer PC-Relative).

FDPIC has some interesting properties. A larger set of pointers can be leaked without revealing the location of .text (via static analysis i.e. known .data pointer can reveal .text via static analysis which can be used for ROP). However this is only partial as pointers to .rodata can still be leaked.

Unfortunately no-MMU Linux is crusty because nobody tests it so your out of luck. Nevertheless FDPIC would be useful for other no-MMU applications where there is more than one ELF loaded in memory or where the ROM/RAM layout (distance between ROM and RAM) is not known at link time. It’s a pity. Also we don’t have ASLR for regular PIC.

2.When executing curl http://www.ocf.berkeley.edu/~qmn/linux/linux-inittab > etc/inittab   I got permission error bash: etc/inittab: Permission denied

Its denied even when I used the sudo command.Any suggestions ?

This is because IO redirection ‘>’ is executed by your shell and not sudo. You are reading the web with sudo. Try piping to tee.

curl https://foo.bar l sudo tee etc/inittab

or use -o

sudo curl -o etc/inittab https://foo.bar

thanks

On Thursday, October 18, 2018 at 11:24:56 AM UTC+5:30, knilaks...@gmail.com wrote:

based on the instructions given in https://github.com/riscv/riscv-tools/tree/new_privileged_isa

I tried to cross compile Linux 4.18.14 kernel.Itried the command  make -j ARCH=riscv

but got some unreference error.ThenI tried  make -j ARCH=riscv CROSS_COMPILE=
risc64-unknown-linux-gnu-

I got the follwing error


Makefile:1027: recipe for target 'vmlinux' failed
arch/riscv/kernel/setup.o: In function `.L24':
setup.c:(.init.text+0x2e2): undefined reference to `swiotlb_init'
Makefile:1027: recipe for target 'vmlinux' failed
make: *** [vmlinux] Error 1




Any suggestions to overcome this?





--
You received this message because you are subscribed to the Google Groups "RISC-V HW Dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email to hw-dev+un...@groups.riscv.org.
To post to this group, send email to hw-...@groups.riscv.org.
Visit this group at https://groups.google.com/a/groups.riscv.org/group/hw-dev/.
To view this discussion on the web visit https://groups.google.com/a/groups.riscv.org/d/msgid/hw-dev/aee5c782-b683-40a3-8d33-dabe5b0e87ef%40groups.riscv.org.

[knilaks...@gmail.com]

Thanks Michael

On Thursday, October 18, 2018 at 11:24:56 AM UTC+5:30, knilaks...@gmail.com wrote:

[knilaks...@gmail.com]

I couldn't save the inittab file

[knilaks...@gmail.com]

I have mounted 64MB portion from disk.The mnt partition is read only.How to make it write enable?

On Thursday, October 18, 2018 at 11:24:56 AM UTC+5:30, knilaks...@gmail.com wrote:

[Tommy Murphy]

On Tuesday, 23 October 2018 16:08:42 UTC+1, knilaks...@gmail.com wrote:

I couldn't save the inittab file

Did you edit/save it as root/sudo? 

[knilaks...@gmail.com]

sudo mount -o loop root.bin mnt

I've used this one

[knilaks...@gmail.com]

dd if=/dev/zero of=root.bin bs=1M count=64

mkfs.ext2 -F root.bin

sudo mount -o loop root.bin mnt

[Tommy Murphy]

On Tuesday, 23 October 2018 16:35:43 UTC+1, knilaks...@gmail.com wrote:

sudo mount -o loop root.bin mnt

I've used this one

Eh? What has that got to do with editing and saving  the file?

You said that you could not save your edits to the inittab file.

I asked if you edited and saved it with root/su privileges?

[knilaks...@gmail.com]

Yes I used to do with sudo privileges