[Qemu-devel] About QEMU for MIPS

[Qemu-devel] About QEMU for MIPS

[Nancy]

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Hi,

1. When QEMU for MIPS support watchpoint debug facility? Any hint or guide
to implement that function?

2. qemu-system-mipsel -M malta -kernel vmlinux-2.6.26-1-4kc-malta -hda
debian_lenny_mipsel_small.qcow2 -append "root=/dev/hda1 console=ttyS0
kgdboc=ttyS0,115200 kgdbwait" -nographic -serial tcp::1234,server -net
nic,model=pcnet -net user

Did I miss something? I cannot see the bootup message in the current client
unless I remove "-serial tcp::1234,server" away. But I need that for kgdb
debug. What is the right way to configure it?

-- 
Best Regards,
Yu Rong Tan

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Re: [Qemu-devel] About QEMU for MIPS

[Antony Pavlov]

On Tue, 29 Oct 2013 21:09:30 +0800
Nancy <nancydreaming@gmail.com> wrote:

Some years ago I have made a set of scripts for building MIPS linux kernel and 
rootfs from scratch and running it under qemu. 
See https://github.com/frantony/clab for details,
especialy see start-qemu.sh script and files in the qemu-configs/malta-linux-gnu
subdirectory.
 
Also see a versatile 'buildroot' software for easy rootfs creation (www.buildroot.org).

> 1. When QEMU for MIPS support watchpoint debug facility? Any hint or guide
> to implement that function?

Run qemu with -S and -s options. Next start your cross gdb (e.g. mips-linux-gdb),
next in the gdb cmdline use command "target remote :1234" to connect to qemu.

> 2. qemu-system-mipsel -M malta -kernel vmlinux-2.6.26-1-4kc-malta -hda
> debian_lenny_mipsel_small.qcow2 -append "root=/dev/hda1 console=ttyS0
> kgdboc=ttyS0,115200 kgdbwait" -nographic -serial tcp::1234,server -net
> nic,model=pcnet -net user
> 
> Did I miss something? I cannot see the bootup message in the current client
> unless I remove "-serial tcp::1234,server" away. But I need that for kgdb
> debug. What is the right way to configure it?

Do you really need this "in-kernel" gdb support? As I have already write,
qemu itself has gdb server functionality support.
 
> -- 
> Best Regards,
> Yu Rong Tan


-- 
-- 
Best regards,
  Antony Pavlov

Re: [Qemu-devel] About QEMU for MIPS

[Nancy]

On Wed, Oct 30, 2013 at 2:43 AM, Antony Pavlov <antonynpavlov@gmail.com> wrote:
> On Tue, 29 Oct 2013 21:09:30 +0800
> Nancy <nancydreaming@gmail.com> wrote:
>
> Some years ago I have made a set of scripts for building MIPS linux kernel and
> rootfs from scratch and running it under qemu.
> See https://github.com/frantony/clab for details,
> especialy see start-qemu.sh script and files in the qemu-configs/malta-linux-gnu
> subdirectory.
>
> Also see a versatile 'buildroot' software for easy rootfs creation (www.buildroot.org).

Wow, what a good Idea to create this tool!  That will save people's time!
I have ran:
$./mk_src_dir.sh
$./build-all.sh
  MKDIR config.gen
  IN    config.gen/arch.in
  IN    config.gen/kernel.in
  IN    config.gen/cc.in
  IN    config.gen/libc.in
  IN    config.gen/debug.in
  CONF  config/config.in
run_with_check: ./ct-ng build.24
[INFO ]  Performing some trivial sanity checks
[INFO ]  Build started 20131030.171948
[INFO ]  Building environment variables
[EXTRA]  Preparing working directories
[ERROR]
[ERROR]    >>
[ERROR]    >>  Error happened in: CT_DoExecLog[scripts/functions]
[ERROR]    >>        called from: main[scripts/crosstool-NG.sh@235]
[ERROR]    >>
[ERROR]    >>  For more info on this error, look at the file: 'build.log'
[ERROR]    >>  There is a list of known issues, some with workarounds, in:
[ERROR]    >>      'docs/B - Known issues.txt'
[ERROR]
[ERROR]    Build failed in step 'Dumping user-supplied crosstool-NG
configuration'
[ERROR]
[ERROR]    (elapsed: 0:00.18)
[00:00] / make[1]: *** [build] Error 1
make: *** [build.24] Error 2
fail: ./ct-ng build.24



>> 1. When QEMU for MIPS support watchpoint debug facility? Any hint or guide
>> to implement that function?
>
> Run qemu with -S and -s options. Next start your cross gdb (e.g. mips-linux-gdb),
> next in the gdb cmdline use command "target remote :1234" to connect to qemu.

Thank you very much! I did not use cross gdb so I got wrong, then I
saw the QEMU internal paper, it says current MIPS limitation do not
implement watchpoint debug facility, I though it was QEMU bug.  So
give up QEMU internal gdb try.
Now it work with cross gdb, Thank you very much Sir :-)

By the way, do you know how to compile linux kernel with -O0 option to
forbid gdb pointer jump back and forth...


>> 2. qemu-system-mipsel -M malta -kernel vmlinux-2.6.26-1-4kc-malta -hda
>> debian_lenny_mipsel_small.qcow2 -append "root=/dev/hda1 console=ttyS0
>> kgdboc=ttyS0,115200 kgdbwait" -nographic -serial tcp::1234,server -net
>> nic,model=pcnet -net user
>>
>> Did I miss something? I cannot see the bootup message in the current client
>> unless I remove "-serial tcp::1234,server" away. But I need that for kgdb
>> debug. What is the right way to configure it?
>
> Do you really need this "in-kernel" gdb support? As I have already write,
> qemu itself has gdb server functionality support.

Though maybe I do not use kgdb, I still want to know the right way to
configure it  ;-)


-- 
Best Regards,
Yu Rong Tan