Messages in this thread | | | Date | Fri, 7 Feb 2020 09:30:03 +0900 | From | Masami Hiramatsu <> | Subject | Re: [for-next][PATCH 04/26] bootconfig: Add Extra Boot Config support |
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On Thu, 6 Feb 2020 18:20:15 +0100 Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> Hi Hiramatsu-san, > > On Thu, Feb 6, 2020 at 3:42 PM Masami Hiramatsu <mhiramat@kernel.org> wrote: > > On Thu, 6 Feb 2020 12:54:05 +0100 > > Borislav Petkov <bp@alien8.de> wrote: > > > On Tue, Jan 14, 2020 at 04:03:20PM -0500, Steven Rostedt wrote: > > > > diff --git a/init/Kconfig b/init/Kconfig > > > > index a34064a031a5..63450d3bbf12 100644 > > > > --- a/init/Kconfig > > > > +++ b/init/Kconfig > > > > @@ -1215,6 +1215,17 @@ source "usr/Kconfig" > > > > > > > > endif > > > > > > > > +config BOOT_CONFIG > > > > + bool "Boot config support" > > > > + select LIBXBC > > > > + default y > > > > > > Any particular reason this is default y? Why should it be enabled by > > > default on all boxes? > > > > Oh, you are not the first person asked that :) > > > > https://lkml.org/lkml/2019/12/9/563 > > > > And yes, I think this is important that will useful for most developers > > and admins. Since the bootconfig already covers kernel and init options, > > this can be a new standard way to pass args to kernel boot. > > > > And as I reported above thread, the memory footpoint of view, most code > > and working memory are released after boot. Also, as Linus's suggested, > > now this feature is enabled only if user gives "bootconfig" on the kernel > > command line. So the side effect is minimized. > > With m68k/atari_defconfig, bloat-o-meter says: > > add/remove: 39/0 grow/shrink: 2/0 up/down: 13086/0 (13086) > > which is IMHO not that small for a "default y" option that may or may not > be used. > > Especially: > > Function old new delta > xbc_nodes - 8192 +8192 > > Any chance xbc_nodes can be allocated dynamically, and only when needed?
Yes, I think we can use memblock to allocate it. However, this xbc_nodes is __init_data, which is released right after boot. So I think it should be OK except for your system doesn't have user space...
> Yes, there are industrial products running Linux on a current ARM SoC > using the builtin 8 or 10 MiB of SRAM (+ XIP for the kernel), so these > definitely want to say CONFIG_BOOT_CONFIG=n.
I think for such products the kernel must be tuned with custom config, and you can say CONFIG_BOOT_CONFIG=n. That is a configurable feature.
Thank you,
> > Thanks! > > add/remove: 39/0 grow/shrink: 2/0 up/down: 13086/0 (13086) > Function old new delta > xbc_nodes - 8192 +8192 > xbc_init - 854 +854 > start_kernel 1020 1580 +560 > copy_xbc_key_value_list - 362 +362 > __xbc_parse_value - 324 +324 > xbc_snprint_cmdline - 294 +294 > xbc_node_compose_key_after - 266 +266 > xbc_namebuf - 256 +256 > xbc_add_sibling - 254 +254 > xbc_node_find_next_leaf - 186 +186 > xbc_node_find_child - 176 +176 > __xbc_add_key - 162 +162 > proc_boot_config_init - 124 +124 > xbc_make_cmdline - 122 +122 > xbc_node_find_value - 104 +104 > xbc_node_find_next_key_value - 102 +102 > __xbc_close_brace - 92 +92 > find_match_node - 80 +80 > __xbc_parse_keys - 78 +78 > xbc_node_get_data - 64 +64 > xbc_parse_key - 60 +60 > skip_comment - 48 +48 > xbc_destroy_all - 42 +42 > xbc_node_get_parent - 38 +38 > xbc_parse_error - 36 +36 > xbc_node_get_child - 34 +34 > xbc_node_get_next - 32 +32 > boot_config_checksum - 30 +30 > boot_config_proc_show - 26 +26 > xbc_root_node - 20 +20 > kzalloc.constprop 810 830 +20 > xbc_node_index - 14 +14 > xbc_node_num - 4 +4 > xbc_data_size - 4 +4 > xbc_data - 4 +4 > saved_boot_config - 4 +4 > last_parent - 4 +4 > extra_init_args - 4 +4 > extra_command_line - 4 +4 > __initcall_proc_boot_config_init5 - 4 +4 > xbc_debug_dump - 2 +2 > Total: Before=3688860, After=3701946, chg +0.35% > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds
-- Masami Hiramatsu <mhiramat@kernel.org>
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