Re: BUG: mips: errors when compiling kernel with a large initramfs

[Xu, Yanfei]

On 4/7/20 8:25 PM, Jiaxun Yang wrote:
> On Tue, 7 Apr 2020 17:58:23 +0800
> "Xu, Yanfei" <yanfei.xu@xxxxxxxxxxxxx> wrote:
>
> > Hi,
> >
> >
> > It fails to compile mips kernel with large initramfs (at link time).
> >
> > kernel version: 5.6.0
> >
> >
> > Steps to reproduce:
> >
> > 1. git clone mainline kernel
> >
> > 2. set ARCH=mips and CROSS_COMPILE=mips-linux-gnu-
> >
> > 3. make defconfig
> >
> > 4.enable initramfs support and set the path about initramfs source
> > file
> >
> > 5.make -j24
> >
> > [KEY] when your initramfs files is too large, and cause
> > usr/initramfs_data.cpio.gz
> >
> > compiled is larger than 225M, you will get the following error. BTW,
> > x86 doesn't
> >
> > have this issue that I have tested.
> >
> > ------------------------------error
> > messages-----------------------------------------
> >
> >   Â CHKÂÂÂÂ include/generated/compile.h
> >   Â LDÂÂÂÂÂ vmlinux.o
> >   Â MODPOST vmlinux.o
> >   Â MODINFO modules.builtin.modinfo
> >   Â GENÂÂÂÂ modules.builtin
> >   Â LDÂÂÂÂÂ .tmp_vmlinux.kallsyms1
> > kernel/configs.o: In function `ikconfig_cleanup':
> > /home/wrsadmin/work/linux/kernel/linux-master/kernel/configs.c:72:(.exit.text+0x8):
> > relocation truncated to fit: R_MIPS_26 against `remove_proc_entry'
> > fs/binfmt_script.o: In function `exit_script_binfmt':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/binfmt_script.c:165:(.exit.text+0x4):
> > relocation truncated to fit: R_MIPS_26 against `unregister_binfmt'
> > fs/binfmt_elf.o: In function `exit_elf_binfmt':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/binfmt_elf.c:2393:(.exit.text+0x4):
> > relocation truncated to fit: R_MIPS_26 against `unregister_binfmt'
> > fs/mbcache.o: In function `mbcache_exit':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/mbcache.c:429:(.exit.text+0x4):
> > relocation truncated to fit: R_MIPS_26 against `kmem_cache_destroy'
> > fs/nfs_common/grace.o: In function `exit_grace':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/nfs_common/grace.c:133:(.exit.text+0x4):
> > relocation truncated to fit: R_MIPS_26 against
> > `unregister_pernet_subsys' fs/ext4/super.o: In function
> > `ext4_destroy_lazyinit_thread':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/ext4/super.c:3456:(.exit.text+0x24):
> > relocation truncated to fit: R_MIPS_26 against `kthread_stop'
> > fs/ext4/super.o: In function `unregister_as_ext2':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/ext4/super.c:6126:(.exit.text+0x30):
> > relocation truncated to fit: R_MIPS_26 against
> > `unregister_filesystem' fs/ext4/super.o: In function
> > `unregister_as_ext3':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/ext4/super.c:6155:(.exit.text+0x3c):
> > relocation truncated to fit: R_MIPS_26 against
> > `unregister_filesystem' fs/ext4/super.o: In function `ext4_exit_fs':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/ext4/super.c:6261:(.exit.text+0x48):
> > relocation truncated to fit: R_MIPS_26 against
> > `unregister_filesystem' fs/ext4/super.o: In function
> > `destroy_inodecache':
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/ext4/super.c:1218:(.exit.text+0x50):
> > relocation truncated to fit: R_MIPS_26 against `rcu_barrier'
> > /home/wrsadmin/work/linux/kernel/linux-master/fs/ext4/super.c:1219:(.exit.text+0x5c):
> > additional relocation overflows omitted from the output
> > Makefile:1086: recipe for target 'vmlinux' failed make[1]: ***
> > [vmlinux] Error 1 Makefile:1058: recipe for target
> > 'autoksyms_recursive' failed make: *** [autoksyms_recursive] Error 2
> >
> >
> > Any comment will be appreciated.
> Actually I think that won't work even if you managed to workaround
> reloc issue.
>
> MIPS have limited LOW MEM range accessible via KSEG0 (512M, but can be
> less if your system place some MMIO register in that range). Kernel
> image will be placed here together with built-in initramfs, and a
> lot of memory like Page Table can only be allocated from here.
>
> Such a huge initrd will occupy the whole LOW MEM range leaving no space
> for others.

As you said, it is really a problem about a huge initramfs. I'll pay 
attention

about this point.

> It seems like your system is 32bit, we have no solution for that
> hardware limitaion. For 64bit system you may try to move your kernel
> into XKPHYS instead of KSEG0.

Yes, it is a 32bit system. And thanks for your workaround about 64bit.

: )

Thanks,

Yanfei

> Thanks
>
> --
> Jiaxun Yang
>
> > Thanks,
> >
> > Yanfei