Messages in this thread | | | Subject | Re: [PATCH v4 RFT 1/2] powerpc/fadump: reduce memory consumption for capture kernel | From | Hari Bathini <> | Date | Tue, 2 May 2017 22:14:48 +0530 |
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Hi Michal,
On Tuesday 02 May 2017 09:26 PM, Michal Suchanek wrote: > With fadump (dump capture) kernel booting like a regular kernel, it almost > needs the same amount of memory to boot as the production kernel, which is > unwarranted for a dump capture kernel. But with no option to disable some > of the unnecessary subsystems in fadump kernel, that much memory is wasted > on fadump, depriving the production kernel of that memory. > > Introduce kernel parameter 'fadump_append=' that would take regular kernel > parameters to be appended when fadump is active. > This 'fadump_append=' parameter can be leveraged to pass parameters like > nr_cpus=1, cgroup_disable=memory and numa=off, to disable unwarranted > resources/subsystems. > > Also, ensure the log "Firmware-assisted dump is active" is printed early > in the boot process to put the subsequent fadump messages in context. > > Suggested-by: Michael Ellerman <mpe@ellerman.id.au> > Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com> > Signed-off-by: Michal Suchanek <msuchanek@suse.de> > --- > v4: > - use space separated arguments instead of comma separated > - do not append parameters when fadummp is disabled > --- > arch/powerpc/kernel/fadump.c | 27 ++++++++++++++++++++++++--- > 1 file changed, 24 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c > index ebf2e9c..e0c728a 100644 > --- a/arch/powerpc/kernel/fadump.c > +++ b/arch/powerpc/kernel/fadump.c > @@ -79,8 +79,10 @@ int __init early_init_dt_scan_fw_dump(unsigned long node, > * dump data waiting for us. > */ > fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL); > - if (fdm_active) > + if (fdm_active) { > + pr_info("Firmware-assisted dump is active.\n"); > fw_dump.dump_active = 1; > + } > > /* Get the sizes required to store dump data for the firmware provided > * dump sections. > @@ -263,8 +265,12 @@ int __init fadump_reserve_mem(void) > { > unsigned long base, size, memory_boundary; > > - if (!fw_dump.fadump_enabled) > + if (!fw_dump.fadump_enabled) { > + if (fw_dump.dump_active) > + pr_warn("Firmware-assisted dump was active but kernel" > + " booted with fadump disabled!\n"); > return 0; > + } > > if (!fw_dump.fadump_supported) { > printk(KERN_INFO "Firmware-assisted dump is not supported on" > @@ -304,7 +310,6 @@ int __init fadump_reserve_mem(void) > memory_boundary = memblock_end_of_DRAM(); > > if (fw_dump.dump_active) { > - printk(KERN_INFO "Firmware-assisted dump is active.\n"); > /* > * If last boot has crashed then reserve all the memory > * above boot_memory_size so that we don't touch it until > @@ -363,6 +368,22 @@ unsigned long __init arch_reserved_kernel_pages(void) > return memblock_reserved_size() / PAGE_SIZE; > } > > +/* Look for fadump_append= cmdline option. */ > +static int __init early_fadump_append_param(char *p) > +{ > + if (!p) > + return 1; > + > + if (fw_dump.fadump_enabled && fw_dump.dump_active) { > + pr_info("enforcing additional parameters (%s) passed through " > + "'fadump_append=' parameter\n", p); > + parse_early_options(p); > + } > + > + return 0; > +} > +early_param("fadump_append", early_fadump_append_param); > + > /* Look for fadump= cmdline option. */ > static int __init early_fadump_param(char *p) > {
I don't think this addresses Michael's concern in v3.. IIUC, we should actually be editing boot_command_line early in the boot process instead of using parse_early_options() to enforce the additional parameters..
Thanks Hari
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