Overriding/concatenating kernel command-line with bootargs from dtb?
Hi all,
I have a specific use case, where two boards using the same SoC have different UART speeds, which is something that I have specified in their corresponding dts files. In order to make sure people don't mess up the configuration, I prefer not to rely on the bootloader-supplied kernel-command line.
I was kind of expecting that ARM_ATAG_DTB_COMPAT + CMDLINE_EXTEND would actually concatenate the kernel command-line with the bootargs provided from dtb.
Is this something someone else would need? If so, shall we just make that happen when the two config symbols mentionned above are enabled, or shall we introduce a 4th kernel command line handling strategy?
Thank you for your answers.
Signature · 1 line
Florian
Quoted 7 lines · Florian Fainelli
Hi all,
I have a specific use case, where two boards using the same SoC have different UART speeds, which is something that I have specified in their corresponding dts files. In order to make sure people don't mess up the configuration, I prefer not to rely on the bootloader-supplied kernel-command line.
Quoted 7 lines
I was kind of expecting that
ARM_ATAG_DTB_COMPAT+CMDLINE_EXTENDwould actually concatenate the kernel command-line with the bootargs provided from dtb.Is this something someone else would need? If so, shall we just make that happen when the two config symbols mentionned above are enabled, or shall we introduce a 4th kernel command line handling strategy?
The former please. The logic in parse_tag_cmdline() needs to be duplicated in early_init_dt_scan_chosen(). CONFIG_CMDLINE_FORCE is already implemented, so only CONFIG_CMDLINE_EXTEND is missing.
Nicolas
Quoted 11 lines · Florian Fainelli
Hi all,
I have a specific use case, where two boards using the same SoC have different UART speeds, which is something that I have specified in their corresponding dts files. In order to make sure people don't mess up the configuration, I prefer not to rely on the bootloader-supplied kernel-command line.
I was kind of expecting that
ARM_ATAG_DTB_COMPAT+CMDLINE_EXTENDwould actually concatenate the kernel command-line with the bootargs provided from dtb.
Quoted 5 lines
Is this something someone else would need? If so, shall we just make that happen when the two config symbols mentionned above are enabled, or shall we introduce a 4th kernel command line handling strategy?
Thank you for your answers.
There was a patch to do this:
http://www.mail-archive.com/devicetree-discuss at lists.ozlabs.org/msg10448.html
Please comment if this works for you.
Rob
Hi Rob,
Quoted 4 lines · On Monday 11 June 2012 09:34:33 Rob Herring wrote:
Quoted 3 lines · Florian Fainelli
Hi all,
I have a specific use case, where two boards using the same SoC have
different
Quoted 1 line
Quoted 1 line
UART speeds, which is something that I have specified in their
corresponding
Quoted 5 lines
Quoted 5 lines
dts files. In order to make sure people don't mess up the configuration, I prefer not to rely on the bootloader-supplied kernel-command line.
I was kind of expecting that
ARM_ATAG_DTB_COMPAT+CMDLINE_EXTENDwould actually concatenate the kernel command-line with the bootargs provided
from
Quoted 4 lines
Quoted 4 lines
dtb.
Is this something someone else would need? If so, shall we just make that happen when the two config symbols mentionned above are enabled, or shall
we
Quoted 7 lines
Quoted 3 lines
introduce a 4th kernel command line handling strategy?
Thank you for your answers.
There was a patch to do this:
discuss at lists.ozlabs.org/msg10448.html
Quoted 2 lines
Please comment if this works for you.
This patch indeeds work fine for me when I disable ARM_ATAG_DTB_COMPAT. If I let it turned on the chosen node is correctly scanned, but its value, is the one coming from tag_cmdline() which is actually the bootloader supplied commad-line. I will cook up a patch for this, because I expect the 3 command- lines to be concatened in the end (built-in, atag and dtb).
I don't see any comments from Ben or anyone after Doug sent his version 2 of the patch, is there any reason not to merge it?
Signature · 1 line
Florian