L4Linux with L4Re and Fiasco.OC-UX

Adam Lackorzynski adam at os.inf.tu-dresden.de
Wed Apr 3 07:56:32 CEST 2019

Hi Paul,

On Thu Mar 28, 2019 at 23:28:17 +0100, Paul Boddie wrote:
> I have been looking at trying out L4Linux in UX mode as a first step towards 
> its use on "native" Fiasco, and I seem to be experiencing a problem with 
> launching the Linux kernel itself.
> I have followed the instructions from these pages:
> https://l4linux.org/download.shtml
> https://l4linux.org/build.shtml
> https://l4linux.org/use.shtml
> Specifically, I have an existing build of UX that has been used for some time 
> to develop software. I have updated it to revision 83 and have checked out the 
> l4linux_requirements, which appear to be some packages (rtc and shmc) I 
> already have. I then performed a build once again:
> make O=mybuild
> The L4Linux repository has also been checked out and updated to revision 83. 
> The code has been configured and built using the following invocations:
> make O=mybuild x86_32-ux_defconfig
> make O=mybuild menuconfig # to set the L4Re build directory
> make O=mybuild
> Here, the mybuild directory is distinct from the L4Re mybuild directory.
> For the initial RAM filesystem, I downloaded the ramdisk-x86.rd file, and I 
> run the system as follows:
> make O=mybuild ux E=L4Linux-basic
> After the usual familiar start-up messages, I see this output specific to the 
> configuration being launched:
> ----
> Ned: loading file: 'rom/l4lx.cfg'
> libio: Warning: Query of 'vbus' failed!
> PH  0 offs=00001000 flags=r-x PH-type=0x1
>       virt=00100000 evirt=0053f000
>       phys=00100000 ephys=0053f000
>       f_sz=0043f000 memsz=0043f000
> PH  1 offs=00440000 flags=rw- PH-type=0x1
>       virt=0053f000 evirt=00a58000
>       phys=0053f000 ephys=00a58000
>       f_sz=0006ce9f memsz=00519000
> PH  2 offs=00371ee0 flags=--- PH-type=0x4
>       virt=00470ee0 evirt=00470f1c
>       phys=00470ee0 ephys=00470f1c
>       f_sz=0000003c memsz=0000003c
> Starting binary at 0x100000, argc=6 argv=0xafff4f84 *argv=0xb1007ff4 
> argv0=rom/vmlinuz
> External resolver is at 0xa8000bd0
> L4Re: rom/vmlinuz: Unhandled exception: PC=0x46980b PFA=97d47fe0 LdrFlgs=0
> ----
> In order to try and identify the problem, I used the following command:
> addr2line -e ~/L4/L4Linux/l4linux/mybuild/vmlinux 0x46980b
> This seems to indicate that the point of failure is at line 2727 in 
> arch/l4/kernel/main.c which is the start of this function:
> int __ref L4_CV main(int argc, char **argv)
> So, I wonder what the problem might be that leads to a crash as the main 
> function is being invoked. Have I missed anything obvious?

Guess not except that doing this on UX could be a bit adventurous
nowadays. Which instruction is sitting at 0x46980b?


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