Messages in this thread | | | Date | Tue, 20 Mar 2018 18:12:22 -0700 (PDT) | Subject | Re: [PATCH] of: Respect CONFIG_CMDLINE{,_EXTENED,_FORCE) with no chosen node | From | Palmer Dabbelt <> |
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On Sun, 18 Mar 2018 05:51:50 PDT (-0700), robh@kernel.org wrote: > On Wed, Mar 14, 2018 at 09:31:05AM -0700, Palmer Dabbelt wrote: >> Systems that boot without a chosen node in the device tree should still >> respect the command lines that are built into the kernel. This patch >> avoids bailing out of the command line argument parsing code when there >> is no chosen node in the device tree. This is necessary to boot >> straight to a root file system (ie, without an initramfs) >> >> The intent here is that the only functional change is to copy >> CONFIG_CMDLINE into data if both of them are valid (ie, CONFIG_CMDLINE >> is defined and data is non-null) on systems where there is no chosen >> device tree node. I don't actually know what the return values do so I >> just preserved them. >> >> Thanks to Trung and Moritz for finding the bug during our ELC hackathon >> (and providing the first fix), and Michal for suggesting this fix (which >> is cleaner than what I was doing). I've given this very minimal >> testing: it fixes the RISC-V bug (in conjunction with a patch to move >> from COMMANDLINE_OVERRIDE to COMMANDLINE_FORCE), still works on systems >> with and without the chosen node, and builds on ARM64. >> >> CC: Michael J Clark <mjc@sifive.com> >> CC: Trung Tran <trung.tran@ettus.com> >> CC: Moritz Fischer <mdf@kernel.org> >> Signed-off-by: Palmer Dabbelt <palmer@sifive.com> >> --- >> drivers/of/fdt.c | 14 ++++++++++++-- >> 1 file changed, 12 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c >> index 84aa9d676375..60241b1cb024 100644 >> --- a/drivers/of/fdt.c >> +++ b/drivers/of/fdt.c >> @@ -1084,9 +1084,12 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, >> >> pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname); >> >> - if (depth != 1 || !data || >> + if (!data) >> + goto no_data; > > Just "return 0" here. > >> + >> + if (depth != 1 || >> (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0)) >> - return 0; >> + goto no_chosen; >> >> early_init_dt_check_for_initrd(node); >> >> @@ -1117,6 +1120,13 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, >> >> /* break now */ >> return 1; >> + >> +no_chosen: >> +#ifdef CONFIG_CMDLINE >> + strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE); > > Best case, this is going to needlessly copy the string on every single > node that is not /chosen. > > Worst case, I think this changes behavior. For example, first you copy > CONFIG_CMDLINE into data, then on a later iteration, you strlcat > CONFIG_CMDLINE into data if CONFIG_CMDLINE_EXTEND is enable. There could > also be some unintended behavior if data has a string to start with.
Ah, sorry, I guess I wasn't paying attention -- I assumed this was only called for the relevant node (like the rest of the device tree stuff), and that chosel was just somewhere inside it.
> I'd really like to see this function re-written to just find the /chosen > node and then handle each property one by one. The iterating approach is > silly. I assume it predates libfdt and we didn't have nice functions to > find nodes by path (or any other way). > > I'm working on a patch to re-structure this function. Will send it out > in the next day. > >> +#endif >> +no_data: >> + return 0; >> } >> >> #ifdef CONFIG_HAVE_MEMBLOCK >> -- >> 2.16.1
Thanks. Do you mind CCing me on it? Then I'll figure out a way to make sure our command lines still work.
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