On Thu, Jan 16, 2025 at 04:11:40PM +0300, Dmitry Rokosov wrote: > Hello Quentin, > > On Tue, Jan 14, 2025 at 12:16:35PM +0100, Quentin Schulz wrote: > > Hi Dmitry, > > > > On 12/19/24 10:42 PM, Dmitry Rokosov wrote: > > > Sometimes, it is necessary to provide an additional bootargs string to > > > the kernel command line. > > > > > > We have a real scenario where one U-Boot blob needs to boot several > > > kernel images: the vendor-patched kernel image and the latest upstream > > > kernel image. The Amlogic (Meson architecture) tty driver has different > > > tty suffixes in these kernels: the vendor uses 'ttySx', while the > > > upstream implementation uses 'ttyAMLx'. The initial console setup is > > > provided to the kernel using the kernel command line (bootargs). For the > > > vendor kernel, we should use 'console=ttyS0,115200', while for the > > > upstream kernel, it must be 'console=ttyAML0,115200'. This means we have > > > to use different command line strings depending on the kernel version. > > > > > > > Can't you have both in bootargs to handle both versions of the kernel with > > the same bootargs? > > > > In this case, modifying the kernel source code is necessary, which falls > outside the scope of this review. > > > > To resolve this issue, we cannot use the CMDLINE_EXTEND kernel > > > configuration because it is considered legacy and is not supported for > > > the arm64 architecture. CMDLINE_EXTEND is outdated primarily because we > > > can provide additional command line strings through the > > > 'chosen/bootargs' FDT node. However, U-Boot uses this node to inject the > > > U-Boot bootargs environment variable content, which results in U-Boot > > > silently overriding all data in the 'chosen/bootargs' node. While we do > > > have the board_fdt_chosen_bootargs() board hook to address such issues, > > > this function lacks any FDT context, such as the original value of the > > > 'chosen/bootargs' node. > > > > > > This patch introduces a read-only (RO) fdt_property argument to > > > board_fdt_chosen_bootargs() to share the original 'chosen/bootargs' data > > > with the board code. Consequently, the board developer can decide how to > > > handle this information for their board setup: whether to drop it or > > > merge it with the bootargs environment. > > > > > > Signed-off-by: Dmitry Rokosov <ddroko...@salutedevices.com> > > > --- > > > boot/fdt_support.c | 5 +++-- > > > include/fdt_support.h | 4 +++- > > > 2 files changed, 6 insertions(+), 3 deletions(-) > > > > > > diff --git a/boot/fdt_support.c b/boot/fdt_support.c > > > index > > > 2c39b2dd14b7c447bc4c7c8fad64e22cb00e88e0..49efeec3681f7c97341ccdce596bcaa4e1f037eb > > > 100644 > > > --- a/boot/fdt_support.c > > > +++ b/boot/fdt_support.c > > > @@ -321,7 +321,7 @@ int fdt_kaslrseed(void *fdt, bool overwrite) > > > * board_fdt_chosen_bootargs - boards may override this function to use > > > * alternative kernel command line arguments > > > */ > > > -__weak const char *board_fdt_chosen_bootargs(void) > > > +__weak const char *board_fdt_chosen_bootargs(const struct fdt_property > > > *fdt_ba) > > > { > > > return env_get("bootargs"); > > > } > > > @@ -364,7 +364,8 @@ int fdt_chosen(void *fdt) > > > } > > > } > > > - str = board_fdt_chosen_bootargs(); > > > + str = board_fdt_chosen_bootargs(fdt_get_property(fdt, nodeoffset, > > > + "bootargs", NULL)); > > > if (str) { > > > err = fdt_setprop(fdt, nodeoffset, "bootargs", str, > > > diff --git a/include/fdt_support.h b/include/fdt_support.h > > > index > > > f481881ce640797e0f6204d599f008d0e5dc2bf7..7731feba5f068f82c8ee25f18a9f0e57729e2bd8 > > > 100644 > > > --- a/include/fdt_support.h > > > +++ b/include/fdt_support.h > > > @@ -231,12 +231,14 @@ int board_rng_seed(struct abuf *buf); > > > /** > > > * board_fdt_chosen_bootargs() - arbitrarily amend fdt kernel command > > > line > > > * > > > + * @fdt_ba: FDT chosen/bootargs from the kernel image if available > > > + * > > > > Missing leading / > > > > /chosen/bootargs > > > > +property > > to highlight what this path refers to. > > > > Agree with that, but looks like patch series is already applied... > Sorry..
I saw that and made those changes in the merge commit. -- Tom
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