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. I also do not see how this addresses On Wed, 26 Apr 2017 20:32:55 +1000 Michael Ellerman <m...@ellerman.id.au> wrote: > Hari Bathini <hbath...@linux.vnet.ibm.com> writes: > > > diff --git a/arch/powerpc/kernel/fadump.c > > b/arch/powerpc/kernel/fadump.c index 8ff0dd4..87edc7b 100644 > > --- a/arch/powerpc/kernel/fadump.c > > +++ b/arch/powerpc/kernel/fadump.c > > @@ -338,6 +343,36 @@ unsigned long __init > > arch_reserved_kernel_pages(void) return memblock_reserved_size() / > > PAGE_SIZE; } > > > > +static void __init parse_fadump_append_params(const char *p) > > +{ > > + static char fadump_cmdline[COMMAND_LINE_SIZE] __initdata; > > + char *token; > > + > > + strlcpy(fadump_cmdline, p, COMMAND_LINE_SIZE); > > + token = strchr(fadump_cmdline, ','); > > + while (token) { > > + *token = ' '; > > + token = strchr(token, ','); > > + } > > + > > + pr_info("enforcing additional parameters (%s) passed > > through " > > + "'fadump_append=' parameter\n", fadump_cmdline); > > + parse_early_options(fadump_cmdline); > > Using parse_early_options() means it only works for parameters defined > with early_param() or __setup() doesn't it? > > That might be OK but at least you need to clearly document it. which was your gripe with v4 of the patchset. Unfortunately the flags in Documentation/kernel-parameters.txt do not include a flag that denotes parameters available with parse_early_options - unless it is the KNL flag and is quite bitrotten. Thanks Michal
