On Tue, Dec 13, 2022 at 09:51:33AM +0100, Linus Walleij wrote: > On Mon, Dec 12, 2022 at 7:01 AM Alexander Sverdlin > <alexander.sverdlin@xxxxxxxxx> wrote: > > > I do not read a strict requirement on /chosen node in either ePAPR or in > > Documentation/devicetree. Help text for CONFIG_CMDLINE and > > CONFIG_CMDLINE_EXTEND doesn't make their behavior explicitly dependent on > > the presence of /chosen or the presense of /chosen/bootargs. > > > > However the early check for /chosen and bailing out in > > early_init_dt_scan_chosen() skips CONFIG_CMDLINE handling which is not > > really related to /chosen node or the particular method of passing cmdline > > from bootloader. > > > > This leads to counterintuitive combinations (assuming > > CONFIG_CMDLINE_EXTEND=y): > > > > a) bootargs="foo", CONFIG_CMDLINE="bar" => cmdline=="foo bar" > > b) /chosen missing, CONFIG_CMDLINE="bar" => cmdline=="" > > c) bootargs="", CONFIG_CMDLINE="bar" => cmdline==" bar" > > > > Move CONFIG_CMDLINE handling outside of early_init_dt_scan_chosen() so that > > cases b and c above result in the same cmdline. > > > > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxx> > > Excellent debugging Alexander! > Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx> > > I also think this should go to stable. We have to be careful there. This could change behavior on a working system. A system taking the cmdline entirely from a built kernel and no initrd is going to be pretty customized already, I think they can carry a patch. What platform is this anyways? This has actually been known for some time[1][2]. My concern in the past (besides wanting all the cmdline manipulation being common) was MIPS. MIPS in particular has lots of sources for cmdline and ways to combine it. However, MIPS has since stopped using this code and does their own parsing (not great either IMO). Rob [1] https://lore.kernel.org/all/CAL_Jsq+CgxWbCMz_qwLbMJS3fYwKyCMBGVS501-5ShXywyDAXA@xxxxxxxxxxxxxx/ [2] https://lore.kernel.org/all/CAL_Jsq+n4e5_ptuh89CJibViGS_bgHz0A+Ki-uwtcGU38+mHXQ@xxxxxxxxxxxxxx/
