| Message ID | 150127542322.3236.985689008735814219.stgit@hbathini.in.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
Hello, sorry about the late reply. Looks like I had too much faith in the parse_args sanity. Looking closely the parsing happens in next_arg and only outermost quotes are removed. So presumably >>foo="bar baz"<< gives >>bar baz<< as value and >>foo=bar" baz"<< gives >>bar" baz<< as value. And presumably you can do fadump_extra_args="par1=val1 par2=val2 pa3=val3" and fadump_extra_args=""par="value with spaces""" (each parameter which needs space in separate fadump_extra_args parameter) provided you remove the outermost quotes in the fadump_extra_args handler as well. Wanted to run some tests but did not get around to do it yet. On Sat, 29 Jul 2017 02:27:22 +0530 Hari Bathini <hbathini@linux.vnet.ibm.com> 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_extra_args=' that would take > regular parameters as a space separated quoted string, to be enforced > when fadump is active. This 'fadump_extra_args=' 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> > --- > > Changes from v5: > * Using 'fadump_extra_args=' instead of 'fadump_append=' to pass > additional parameters, to be enforced when fadump is active. > * Using space-separated quoted list as syntax for 'fadump_extra_args=' > parameter. > > > arch/powerpc/include/asm/fadump.h | 2 + > arch/powerpc/kernel/fadump.c | 125 > ++++++++++++++++++++++++++++++++++++- > arch/powerpc/kernel/prom.c | 7 ++ 3 files changed, 131 > insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/include/asm/fadump.h > b/arch/powerpc/include/asm/fadump.h index ce88bbe..98ae009 100644 > --- a/arch/powerpc/include/asm/fadump.h > +++ b/arch/powerpc/include/asm/fadump.h > @@ -208,11 +208,13 @@ extern int early_init_dt_scan_fw_dump(unsigned > long node, const char *uname, int depth, void *data); > extern int fadump_reserve_mem(void); > extern int setup_fadump(void); > +extern void enforce_fadump_extra_args(char *cmdline); > extern int is_fadump_active(void); > extern void crash_fadump(struct pt_regs *, const char *); > extern void fadump_cleanup(void); > > #else /* CONFIG_FA_DUMP */ > +static inline void enforce_fadump_extra_args(char *cmdline) { } > static inline int is_fadump_active(void) { return 0; } > static inline void crash_fadump(struct pt_regs *regs, const char > *str) { } #endif > diff --git a/arch/powerpc/kernel/fadump.c > b/arch/powerpc/kernel/fadump.c index dc0c49c..d8cb829 100644 > --- a/arch/powerpc/kernel/fadump.c > +++ b/arch/powerpc/kernel/fadump.c > @@ -78,8 +78,10 @@ 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. > @@ -332,8 +334,11 @@ 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" @@ -373,7 +378,6 @@ 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 @@ -460,6 +464,121 @@ static int __init > early_fadump_reserve_mem(char *p) } > early_param("fadump_reserve_mem", early_fadump_reserve_mem); > > +#define FADUMP_EXTRA_ARGS_PARAM "fadump_extra_args=" > +#define INIT_ARGS_START "-- " > +#define INIT_ARGS_START_LEN strlen(INIT_ARGS_START) > + > +struct param_info { > + char *params; > + unsigned int len; > + unsigned int index; > +}; > + > +static void __init fadump_update_params(struct param_info > *param_info, > + char *val, unsigned int len, > + bool split_params) > +{ > + bool add_quotes = (split_params ? false : > + ((strchr(val, ' ') != NULL) ? true : > false)); + > + if (add_quotes) > + param_info->params[param_info->index++] = '"'; This is not safe. You do not know if any quotes were removed so you should not blindly add them. Instead you should copy the value at the place where the argument was found (which you currently do not get but could be added in the argument struct or as extra argument to the callback). > + > + strncpy(param_info->params + param_info->index, val, len); > + param_info->index += len; > + > + if (add_quotes) > + param_info->params[param_info->index++] = '"'; > +} > + > +/* > + * Reworks command line parameters and splits 'fadump_extra_args=' > param > + * to enforce the parameters passed through it > + */ > +static int __init fadump_rework_cmdline_params(char *param, char > *val, > + const char *unused, > void *arg) +{ > + unsigned int len; > + struct param_info *param_info = (struct param_info *)arg; > + bool split_params = false; > + > + if (!strncmp(param, FADUMP_EXTRA_ARGS_PARAM, > + (strlen(FADUMP_EXTRA_ARGS_PARAM) - 1))) > + split_params = true; > + > + len = strlen(param); > + fadump_update_params(param_info, param, len, split_params); > + > + len = (val != NULL) ? strlen(val) : 0; > + if (len) { > + param_info->params[param_info->index++] = > + split_params ? ' ' : > '='; > + fadump_update_params(param_info, val, len, > split_params); > + } > + > + param_info->params[param_info->index++] = ' '; > + > + return 0; > +} > + > +/* > + * Replace every occurrence of 'fadump_extra_args="param1 param2 > param3"' > + * in cmdline with 'fadump_extra_args param1 param2 param3' by > stripping > + * off '=' and quotes, if any. This ensures that the additional > parameters > + * passed with 'fadump_extra_args=' are enforced. > + */ > +void __init enforce_fadump_extra_args(char *cmdline) > +{ > + static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata; > + static char init_cmdline[COMMAND_LINE_SIZE] __initdata; > + struct param_info param_info; > + char *args; > + > + if (strstr(cmdline, FADUMP_EXTRA_ARGS_PARAM) == NULL) > + return; > + > + pr_info("Modifying command line to enforce the additional > parameters passed through 'fadump_extra_args='"); + > + param_info.params = cmdline; > + param_info.len = strlen(cmdline); > + param_info.index = 0; > + > + strlcpy(init_cmdline, cmdline, COMMAND_LINE_SIZE); > + > + strlcpy(tmp_cmdline, cmdline, COMMAND_LINE_SIZE); > + while (1) { > + parse_args("fadump params", tmp_cmdline, NULL, 0, 0, > 0, > + ¶m_info, > &fadump_rework_cmdline_params); + You should probably use the argument structure and amend it to include whatever extra information is needed rather than the unknown parameter hook. > + /* > + * parse_args() stops at '--'. Keep going if there > are more > + * parameters as we are supposed to look at all > parameters > + * in this case. Otherwise, break. You should not do this. If people pass fadump_extra_args to init it's their choice. On the other hand, when fadump_extra_args contains a -- any subsequent parameters are turned into init arguments which is probably not wanted. Thanks Michal
Hello Michal, Thanks for the review.. On Tuesday 15 August 2017 04:26 PM, Michal Suchánek wrote: > Hello, > > sorry about the late reply. > > Looks like I had too much faith in the parse_args sanity. > > Looking closely the parsing happens in next_arg and only outermost > quotes are removed. > > So presumably >>foo="bar baz"<< gives >>bar baz<< as value and > >>foo=bar" baz"<< gives >>bar" baz<< as value. Yeah, with no such thing as nested quotes, it can get tricky if quoted params are put inside fadump_extra_args= (fadump_extra_args="a "b c" d e" f g) > And presumably you can do fadump_extra_args="par1=val1 par2=val2 > pa3=val3" and fadump_extra_args=""par="value with > spaces""" (each parameter which needs space in separate > fadump_extra_args parameter) provided you remove the outermost quotes > in the fadump_extra_args handler as well. > > Wanted to run some tests but did not get around to do it yet. > > On Sat, 29 Jul 2017 02:27:22 +0530 > Hari Bathini <hbathini@linux.vnet.ibm.com> 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_extra_args=' that would take >> regular parameters as a space separated quoted string, to be enforced >> when fadump is active. This 'fadump_extra_args=' 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> >> --- >> >> Changes from v5: >> * Using 'fadump_extra_args=' instead of 'fadump_append=' to pass >> additional parameters, to be enforced when fadump is active. >> * Using space-separated quoted list as syntax for 'fadump_extra_args=' >> parameter. >> >> >> arch/powerpc/include/asm/fadump.h | 2 + >> arch/powerpc/kernel/fadump.c | 125 >> ++++++++++++++++++++++++++++++++++++- >> arch/powerpc/kernel/prom.c | 7 ++ 3 files changed, 131 >> insertions(+), 3 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/fadump.h >> b/arch/powerpc/include/asm/fadump.h index ce88bbe..98ae009 100644 >> --- a/arch/powerpc/include/asm/fadump.h >> +++ b/arch/powerpc/include/asm/fadump.h >> @@ -208,11 +208,13 @@ extern int early_init_dt_scan_fw_dump(unsigned >> long node, const char *uname, int depth, void *data); >> extern int fadump_reserve_mem(void); >> extern int setup_fadump(void); >> +extern void enforce_fadump_extra_args(char *cmdline); >> extern int is_fadump_active(void); >> extern void crash_fadump(struct pt_regs *, const char *); >> extern void fadump_cleanup(void); >> >> #else /* CONFIG_FA_DUMP */ >> +static inline void enforce_fadump_extra_args(char *cmdline) { } >> static inline int is_fadump_active(void) { return 0; } >> static inline void crash_fadump(struct pt_regs *regs, const char >> *str) { } #endif >> diff --git a/arch/powerpc/kernel/fadump.c >> b/arch/powerpc/kernel/fadump.c index dc0c49c..d8cb829 100644 >> --- a/arch/powerpc/kernel/fadump.c >> +++ b/arch/powerpc/kernel/fadump.c >> @@ -78,8 +78,10 @@ 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. >> @@ -332,8 +334,11 @@ 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" @@ -373,7 +378,6 @@ 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 @@ -460,6 +464,121 @@ static int __init >> early_fadump_reserve_mem(char *p) } >> early_param("fadump_reserve_mem", early_fadump_reserve_mem); >> >> +#define FADUMP_EXTRA_ARGS_PARAM "fadump_extra_args=" >> +#define INIT_ARGS_START "-- " >> +#define INIT_ARGS_START_LEN strlen(INIT_ARGS_START) >> + >> +struct param_info { >> + char *params; >> + unsigned int len; >> + unsigned int index; >> +}; >> + >> +static void __init fadump_update_params(struct param_info >> *param_info, >> + char *val, unsigned int len, >> + bool split_params) >> +{ >> + bool add_quotes = (split_params ? false : >> + ((strchr(val, ' ') != NULL) ? true : >> false)); + >> + if (add_quotes) >> + param_info->params[param_info->index++] = '"'; > This is not safe. You do not know if any quotes were removed so you > should not blindly add them. Instead you should copy the value at the > place where the argument was found (which you currently do not get but > could be added in the argument struct or as extra argument to the > callback). ok.. >> + >> + strncpy(param_info->params + param_info->index, val, len); >> + param_info->index += len; >> + >> + if (add_quotes) >> + param_info->params[param_info->index++] = '"'; >> +} >> + >> +/* >> + * Reworks command line parameters and splits 'fadump_extra_args=' >> param >> + * to enforce the parameters passed through it >> + */ >> +static int __init fadump_rework_cmdline_params(char *param, char >> *val, >> + const char *unused, >> void *arg) +{ >> + unsigned int len; >> + struct param_info *param_info = (struct param_info *)arg; >> + bool split_params = false; >> + >> + if (!strncmp(param, FADUMP_EXTRA_ARGS_PARAM, >> + (strlen(FADUMP_EXTRA_ARGS_PARAM) - 1))) >> + split_params = true; >> + >> + len = strlen(param); >> + fadump_update_params(param_info, param, len, split_params); >> + >> + len = (val != NULL) ? strlen(val) : 0; >> + if (len) { >> + param_info->params[param_info->index++] = >> + split_params ? ' ' : >> '='; >> + fadump_update_params(param_info, val, len, >> split_params); >> + } >> + >> + param_info->params[param_info->index++] = ' '; >> + >> + return 0; >> +} >> + >> +/* >> + * Replace every occurrence of 'fadump_extra_args="param1 param2 >> param3"' >> + * in cmdline with 'fadump_extra_args param1 param2 param3' by >> stripping >> + * off '=' and quotes, if any. This ensures that the additional >> parameters >> + * passed with 'fadump_extra_args=' are enforced. >> + */ >> +void __init enforce_fadump_extra_args(char *cmdline) >> +{ >> + static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata; >> + static char init_cmdline[COMMAND_LINE_SIZE] __initdata; >> + struct param_info param_info; >> + char *args; >> + >> + if (strstr(cmdline, FADUMP_EXTRA_ARGS_PARAM) == NULL) >> + return; >> + >> + pr_info("Modifying command line to enforce the additional >> parameters passed through 'fadump_extra_args='"); + >> + param_info.params = cmdline; >> + param_info.len = strlen(cmdline); >> + param_info.index = 0; >> + >> + strlcpy(init_cmdline, cmdline, COMMAND_LINE_SIZE); >> + >> + strlcpy(tmp_cmdline, cmdline, COMMAND_LINE_SIZE); >> + while (1) { >> + parse_args("fadump params", tmp_cmdline, NULL, 0, 0, >> 0, >> + ¶m_info, >> &fadump_rework_cmdline_params); + > You should probably use the argument structure and amend it to include > whatever extra information is needed rather than the unknown parameter > hook. I will probably have to change parse_args which I consciously tried to avoid :) >> + /* >> + * parse_args() stops at '--'. Keep going if there >> are more >> + * parameters as we are supposed to look at all >> parameters >> + * in this case. Otherwise, break. > You should not do this. If people pass fadump_extra_args to init it's > their choice. Right. With parse_args() breaking at '--', fadump_extra_args= passed after it will not be updated without calling parse_args again for cmdline from that point on, which is what I meant to convey there.. > On the other hand, when fadump_extra_args contains a -- any subsequent > parameters are turned into init arguments which is probably not wanted. > I prefer to document this and let the user handle the positioning of multiple fadump_extra_args= params.. Thanks Hari
diff --git a/arch/powerpc/include/asm/fadump.h b/arch/powerpc/include/asm/fadump.h index ce88bbe..98ae009 100644 --- a/arch/powerpc/include/asm/fadump.h +++ b/arch/powerpc/include/asm/fadump.h @@ -208,11 +208,13 @@ extern int early_init_dt_scan_fw_dump(unsigned long node, const char *uname, int depth, void *data); extern int fadump_reserve_mem(void); extern int setup_fadump(void); +extern void enforce_fadump_extra_args(char *cmdline); extern int is_fadump_active(void); extern void crash_fadump(struct pt_regs *, const char *); extern void fadump_cleanup(void); #else /* CONFIG_FA_DUMP */ +static inline void enforce_fadump_extra_args(char *cmdline) { } static inline int is_fadump_active(void) { return 0; } static inline void crash_fadump(struct pt_regs *regs, const char *str) { } #endif diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c index dc0c49c..d8cb829 100644 --- a/arch/powerpc/kernel/fadump.c +++ b/arch/powerpc/kernel/fadump.c @@ -78,8 +78,10 @@ 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. @@ -332,8 +334,11 @@ 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" @@ -373,7 +378,6 @@ 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 @@ -460,6 +464,121 @@ static int __init early_fadump_reserve_mem(char *p) } early_param("fadump_reserve_mem", early_fadump_reserve_mem); +#define FADUMP_EXTRA_ARGS_PARAM "fadump_extra_args=" +#define INIT_ARGS_START "-- " +#define INIT_ARGS_START_LEN strlen(INIT_ARGS_START) + +struct param_info { + char *params; + unsigned int len; + unsigned int index; +}; + +static void __init fadump_update_params(struct param_info *param_info, + char *val, unsigned int len, + bool split_params) +{ + bool add_quotes = (split_params ? false : + ((strchr(val, ' ') != NULL) ? true : false)); + + if (add_quotes) + param_info->params[param_info->index++] = '"'; + + strncpy(param_info->params + param_info->index, val, len); + param_info->index += len; + + if (add_quotes) + param_info->params[param_info->index++] = '"'; +} + +/* + * Reworks command line parameters and splits 'fadump_extra_args=' param + * to enforce the parameters passed through it + */ +static int __init fadump_rework_cmdline_params(char *param, char *val, + const char *unused, void *arg) +{ + unsigned int len; + struct param_info *param_info = (struct param_info *)arg; + bool split_params = false; + + if (!strncmp(param, FADUMP_EXTRA_ARGS_PARAM, + (strlen(FADUMP_EXTRA_ARGS_PARAM) - 1))) + split_params = true; + + len = strlen(param); + fadump_update_params(param_info, param, len, split_params); + + len = (val != NULL) ? strlen(val) : 0; + if (len) { + param_info->params[param_info->index++] = + split_params ? ' ' : '='; + fadump_update_params(param_info, val, len, split_params); + } + + param_info->params[param_info->index++] = ' '; + + return 0; +} + +/* + * Replace every occurrence of 'fadump_extra_args="param1 param2 param3"' + * in cmdline with 'fadump_extra_args param1 param2 param3' by stripping + * off '=' and quotes, if any. This ensures that the additional parameters + * passed with 'fadump_extra_args=' are enforced. + */ +void __init enforce_fadump_extra_args(char *cmdline) +{ + static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata; + static char init_cmdline[COMMAND_LINE_SIZE] __initdata; + struct param_info param_info; + char *args; + + if (strstr(cmdline, FADUMP_EXTRA_ARGS_PARAM) == NULL) + return; + + pr_info("Modifying command line to enforce the additional parameters passed through 'fadump_extra_args='"); + + param_info.params = cmdline; + param_info.len = strlen(cmdline); + param_info.index = 0; + + strlcpy(init_cmdline, cmdline, COMMAND_LINE_SIZE); + + strlcpy(tmp_cmdline, cmdline, COMMAND_LINE_SIZE); + while (1) { + parse_args("fadump params", tmp_cmdline, NULL, 0, 0, 0, + ¶m_info, &fadump_rework_cmdline_params); + + /* + * parse_args() stops at '--'. Keep going if there are more + * parameters as we are supposed to look at all parameters + * in this case. Otherwise, break. + */ + args = strstr(init_cmdline + param_info.index, INIT_ARGS_START); + if (args == NULL) + break; + + strncpy(param_info.params + param_info.index, + INIT_ARGS_START, INIT_ARGS_START_LEN); + param_info.index += INIT_ARGS_START_LEN; + strlcpy(tmp_cmdline, (args + INIT_ARGS_START_LEN), + (COMMAND_LINE_SIZE - param_info.index)); + } + + /* + * Length of the processed cmdline could come down owing to the + * stripping of quotes. Fill that much length with '\0' to + * compensate for that. + */ + if (param_info.len > param_info.index) { + memset(param_info.params + param_info.index, '\0', + (param_info.len - param_info.index)); + } + + pr_info("Modified command line: %s\n", cmdline); +} + static int register_fw_dump(struct fadump_mem_struct *fdm) { int rc, err; diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c index f830562..2e6f4021 100644 --- a/arch/powerpc/kernel/prom.c +++ b/arch/powerpc/kernel/prom.c @@ -693,6 +693,13 @@ void __init early_init_devtree(void *params) of_scan_flat_dt(early_init_dt_scan_root, NULL); of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL); + /* + * Look for 'fadump_extra_args=' parameter and enfore the additional + * parameters passed to it if fadump is active. + */ + if (is_fadump_active()) + enforce_fadump_extra_args(boot_command_line); + parse_early_param(); /* make sure we've parsed cmdline for mem= before this */
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_extra_args=' that would take regular parameters as a space separated quoted string, to be enforced when fadump is active. This 'fadump_extra_args=' 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> --- Changes from v5: * Using 'fadump_extra_args=' instead of 'fadump_append=' to pass additional parameters, to be enforced when fadump is active. * Using space-separated quoted list as syntax for 'fadump_extra_args=' parameter. arch/powerpc/include/asm/fadump.h | 2 + arch/powerpc/kernel/fadump.c | 125 ++++++++++++++++++++++++++++++++++++- arch/powerpc/kernel/prom.c | 7 ++ 3 files changed, 131 insertions(+), 3 deletions(-)