On Friday 12 May 2017 09:12 PM, Michal Suchánek wrote:
On Fri, 12 May 2017 15:15:33 +0530
Hari Bathini <hbath...@linux.vnet.ibm.com> wrote:
On Thursday 11 May 2017 06:46 PM, Michal Suchánek wrote:
On Thu, 11 May 2017 02:00:11 +0530
Hari Bathini <hbath...@linux.vnet.ibm.com> wrote:
Hello Michal,
On Wednesday 10 May 2017 09:31 PM, Michal Suchánek wrote:
Hello,
On Wed, 03 May 2017 23:52:52 +0530
Hari Bathini <hbath...@linux.vnet.ibm.com> wrote:
With the introduction of 'fadump_append=' parameter to pass
additional parameters to fadump (capture) kernel, update
documentation about it.
Signed-off-by: Hari Bathini <hbath...@linux.vnet.ibm.com>
---
Changes from v4:
* Based on top of patchset that includes
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=akpm&id=05f383cdfba8793240e73f9a9fbff4e25d66003f
Documentation/powerpc/firmware-assisted-dump.txt | 10
+++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/Documentation/powerpc/firmware-assisted-dump.txt
b/Documentation/powerpc/firmware-assisted-dump.txt index
8394bc8..6327193 100644 ---
a/Documentation/powerpc/firmware-assisted-dump.txt +++
b/Documentation/powerpc/firmware-assisted-dump.txt @@ -162,7
+162,15 @@ How to enable firmware-assisted dump (fadump):
1. Set config option CONFIG_FA_DUMP=y and build kernel.
2. Boot into linux kernel with 'fadump=on' kernel cmdline
option. -3. Optionally, user can also set 'crashkernel=' kernel
cmdline +3. A user can pass additional command line parameters
as a comma
+ separated list through 'fadump_append=' parameter, to be
enforced
+ when fadump is active. For example, if parameters like
nr_cpus=1,
+ numa=off & udev.children-max=2 are to be enforced when fadump
is
+ active,
'fadump_append=nr_cpus=1,numa=off,udev.children-max=2'
+ can be passed in command line, which will be replaced with
+ "nr_cpus=1 numa=off udev.children-max=2" when fadump is
active.
+ This helps in reducing memory consumption during dump
capture. +4. Optionally, user can also set 'crashkernel=' kernel
cmdline to specify size of the memory to reserve for boot memory
dump preservation.
Writing your own deficient parser for comma separated arguments
when perfectly fine parser for space separated quoted arguments
exists in the kernel and the bootloader does not seem like a good
idea to me.
Couple of things that prompted me for v5 are:
1. Using parse_early_options() limits the kind of parameters
that can be passed to fadump capture kernel. Passing
parameters like systemd.unit= & udev.childern.max= has no effect
with v4. Updating
boot_command_line parameter, when fadump is active, seems a
better alternative.
2. Passing space-separated quoted arguments is not working
as intended with lilo. Updating bootloader with the below
entry in /etc/lilo.conf file results in a missing append
entry in /etc/yaboot.conf file.
append = "quiet sysrq=1 insmod=sym53c8xx insmod=ipr
crashkernel=512M-:256M fadump_append=\"nr_cpus=1 numa=off
udev.children-max=2\""
Meaning that a script that emulates LILO semantics on top of yaboot
which is completely capable of passing qouted space separated
arguments fails. IMHO it is more reasonable to fix the script or
whatever adaptation layer or use yaboot directly than working
around bug in said script by introducing a new argument parser in
the kernel.
Hmmm.. while trying to implement space-separated parameter list with
quotes as syntax for fadump_append parameter, noticed that it can
make implemenation
more vulnerable. Here are some problems I am facing while
implementing this..
How so?
presumably you can reuse parse_args even if you do not register with
early_param and call it yourself. Then your parsing of fadump_append is
I wasn't aware of that. Thanks for pointing it out, Michal.
Will try to use parse_args and get back.
Thanks
Hari
