Messages in this thread | | | Date | Wed, 16 Mar 2022 15:06:17 +0100 | From | Padmanabha Srinivasaiah <> | Subject | Re: tracing : bootconfig : Early boot config for non intrd systems |
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Hello Masami Hiramatsu,
On Sat, Mar 12, 2022 at 03:53:58PM +0900, Masami Hiramatsu wrote: > Hello Padmanabha, > > On Wed, 9 Mar 2022 20:06:51 +0100 > Padmanabha Srinivasaiah <treasure4paddy@gmail.com> wrote: > > > On Wed, Mar 09, 2022 at 05:01:24PM +0900, Masami Hiramatsu wrote: > > > On Tue, 8 Mar 2022 18:48:29 +0100 > > > Padmanabha Srinivasaiah <treasure4paddy@gmail.com> wrote: > > > > > > > Hello Masami Hiramatsu, > > > > > > > > On Tue, Mar 08, 2022 at 04:36:00PM +0900, Masami Hiramatsu wrote: > > > > > Hello Padmanabha, > > > > > > > > > > On Mon, 7 Mar 2022 19:40:11 +0100 > > > > > Padmanabha Srinivasaiah <treasure4paddy@gmail.com> wrote: > > > > > > > > > > > Hello Masami Hiramatsu, > > > > > > > > > > > > Thanks for detailed explanation on boot time tracing using early boot configuration file. > > > > > > https://linuxfoundation.org/wp-content/uploads/boottrace-LF-live-2021-update.pdf > > > > > > > > > > > > Also for https://lwn.net/Articles/806002/. > > > > > > > > > > > > Latter link also states we can embed boot config into the kernel image for non intrd based system. > > > > > > > > > > Ah, that was an original plan, but since no one interested in, I didn't implement it. > > > > > So we still need the initrd for bootconfig. > > > > > > > > > Ok. > > > > > > > > > > > > I tried searching mailing lists not able to find pointer for same. > > > > > > > > > > > > A hint/pointer on how-to will be very helpful. > > > > > > > > > > BTW, what is your problem, could you share your use-case? > > > > > > > > > > > > > I have hetrogenous system which donot use intrd. > > > > > > > > The use-case is to capture __system wide__ event based tracing for > > > > boot-up sequence, which also covers early stage of default init programs > > > > used. > > > > > > > > As buffer size is limited, will have hand-picked events set configured. > > > > > > Hm, so I guess you will boot linux from your custom bootloader (or binary loader on sub processor?). > > > > > Yes, customised implemation which loads linux. > > > > > Can you even try to add a dummy initrd? or are you OK to rebuild kernel for embedding the bootconfig data? > > Yes, re-building the kernel image to appended bootconfig data is feasable option. > > > > OK, please try below patch. You can embed your bootconfig in the kernel via > CONFIG_EMBED_BOOT_CONFIG_FILE. > Thank you Masmi, so kind of you. Will test the latest patchset and report the results. > > From 7478a8fbfe4669ee61fcb12b85b36d7e36f992ba Mon Sep 17 00:00:00 2001 > From: Masami Hiramatsu <mhiramat@kernel.org> > Date: Sat, 12 Mar 2022 14:59:30 +0900 > Subject: [PATCH] bootconfig: Support embedding a bootconfig file in kernel > > This allows kernel developer to embed a default bootconfig file in > the kernel instead of embedding it in the initrd. This will be good > for who are using the kernel without initrd, or who needs a default > bootconfigs. > This needs 2 options: CONFIG_EMBED_BOOT_CONFIG=y and set the file > name to CONFIG_EMBED_BOOT_CONFIG_FILE. > Note that you still need 'bootconfig' command line option to load the > embedded bootconfig. And if you boot with the initrd which has another > bootconfig, the kernel will use the bootconfig in the initrd, instead > of embedding one. > > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> > --- > include/linux/bootconfig.h | 10 ++++++++++ > init/Kconfig | 19 +++++++++++++++++++ > init/main.c | 25 +++++++++++++------------ > lib/bootconfig.c | 23 +++++++++++++++++++++++ > 4 files changed, 65 insertions(+), 12 deletions(-) > > diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h > index a4665c7ab07c..5dbda5e3e9bb 100644 > --- a/include/linux/bootconfig.h > +++ b/include/linux/bootconfig.h > @@ -289,4 +289,14 @@ int __init xbc_get_info(int *node_size, size_t *data_size); > /* XBC cleanup data structures */ > void __init xbc_exit(void); > > +/* XBC embedded bootconfig data in kernel */ > +#ifdef CONFIG_EMBED_BOOT_CONFIG > +char * __init xbc_get_embedded_bootconfig(size_t *size); > +#else > +static inline char *xbc_get_embedded_bootconfig(size_t *size) > +{ > + return NULL; > +} > +#endif > + > #endif > diff --git a/init/Kconfig b/init/Kconfig > index e9119bf54b1f..1b736ac7f90d 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1357,6 +1357,25 @@ config BOOT_CONFIG > > If unsure, say Y. > > +config EMBED_BOOT_CONFIG > + bool "Embed bootconfig file in the kernel" > + depends on BOOT_CONFIG > + default n > + help > + Embed a bootconfig file given by EMBED_BOOT_CONFIG_FILE in the > + kernel. Usually, the bootconfig file is loaded with the initrd > + image. But if the system doesn't support initrd, this option will > + help you by embedding a bootconfig file while building the kernel. > + > + If unsure, say N. > + > +config EMBED_BOOT_CONFIG_FILE > + string "Embedded bootconfig file path" > + default "" > + depends on EMBED_BOOT_CONFIG > + help > + Specify a bootconfig file which will be embedded to the kernel. > + > choice > prompt "Compiler optimization level" > default CC_OPTIMIZE_FOR_PERFORMANCE > diff --git a/init/main.c b/init/main.c > index 65fa2e41a9c0..f371610bc008 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -265,7 +265,7 @@ static int __init loglevel(char *str) > early_param("loglevel", loglevel); > > #ifdef CONFIG_BLK_DEV_INITRD > -static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum) > +static void * __init get_boot_config_from_initrd(size_t *_size) > { > u32 size, csum; > char *data; > @@ -299,12 +299,15 @@ static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum) > return NULL; > } > > + if (xbc_calc_checksum(data, size) != csum) { > + pr_err("bootconfig checksum failed\n"); > + return NULL; > + } > + > /* Remove bootconfig from initramfs/initrd */ > initrd_end = (unsigned long)data; > if (_size) > *_size = size; > - if (_csum) > - *_csum = csum; > > return data; > } > @@ -408,12 +411,15 @@ static void __init setup_boot_config(void) > static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata; > const char *msg; > int pos; > - u32 size, csum; > + size_t size; > char *data, *err; > int ret; > > /* Cut out the bootconfig data even if we have no bootconfig option */ > - data = get_boot_config_from_initrd(&size, &csum); > + data = get_boot_config_from_initrd(&size); > + /* If there is no bootconfig in initrd, try embedded one. */ > + if (!data) > + data = xbc_get_embedded_bootconfig(&size); > > strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE); > err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL, > @@ -432,16 +438,11 @@ static void __init setup_boot_config(void) > } > > if (size >= XBC_DATA_MAX) { > - pr_err("bootconfig size %d greater than max size %d\n", > + pr_err("bootconfig size %ld greater than max size %d\n", > size, XBC_DATA_MAX); > return; > } > > - if (xbc_calc_checksum(data, size) != csum) { > - pr_err("bootconfig checksum failed\n"); > - return; > - } > - > ret = xbc_init(data, size, &msg, &pos); > if (ret < 0) { > if (pos < 0) > @@ -451,7 +452,7 @@ static void __init setup_boot_config(void) > msg, pos); > } else { > xbc_get_info(&ret, NULL); > - pr_info("Load bootconfig: %d bytes %d nodes\n", size, ret); > + pr_info("Load bootconfig: %ld bytes %d nodes\n", size, ret); > /* keys starting with "kernel." are passed via cmdline */ > extra_command_line = xbc_make_cmdline("kernel"); > /* Also, "init." keys are init arguments */ > diff --git a/lib/bootconfig.c b/lib/bootconfig.c > index 74f3201ab8e5..bf84f5838c08 100644 > --- a/lib/bootconfig.c > +++ b/lib/bootconfig.c > @@ -12,6 +12,29 @@ > #include <linux/kernel.h> > #include <linux/memblock.h> > #include <linux/string.h> > + > +#ifdef CONFIG_EMBED_BOOT_CONFIG > +asm ( > +" .pushsection .init.data, \"aw\" \n" > +" .global embedded_bootconfig_data \n" > +"embedded_bootconfig_data: \n" > +" .incbin \"" CONFIG_EMBED_BOOT_CONFIG_FILE "\" \n" > +" .global embedded_bootconfig_data_end \n" > +"embedded_bootconfig_data_end: \n" > +" .popsection \n" > +); > + > +extern __visible char embedded_bootconfig_data[]; > +extern __visible char embedded_bootconfig_data_end[]; > + > +char * __init xbc_get_embedded_bootconfig(size_t *size) > +{ > + *size = embedded_bootconfig_data_end - embedded_bootconfig_data; > + return embedded_bootconfig_data; > +} > + > +#endif > + > #else /* !__KERNEL__ */ > /* > * NOTE: This is only for tools/bootconfig, because tools/bootconfig will > -- > 2.25.1 > > > -- > Masami Hiramatsu <mhiramat@kernel.org>
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