| Message ID | 87plyyrupy.fsf@telent.net (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | question: malta doesn't use a1 for fdt from bootloader | expand |
在 2023/12/22 17:51, dan@telent.net 写道: > > Newbie question: > > I noticed while writing some test automation with QEMU and U-Boot that > the Malta kernel appears to ignore any DTB provided by the bootloader, in > favour of using the one embedded into the kernel image. Is there a > reason behind this, or is it just not a thing that's been changed since > the board was converted to use device tree? Hi, It's a bit of history that DeviceTree passed by YAMON bootloader to kernel does not compatible with upstream kernel's devicetree bindings, so we decided to just omit it. > > I patched my own kernel to check $a1 as the "mips generic" kernel does, > and it seems to work, but maybe I'm missing something? I did have to > rebuild U-Boot with different CONFIG options to make use of it (I don't > khow what real hardware Malta uses for a bootloader) so perhaps it has > limited use. > > If the change is acceptable in principle I'll tidy it up and submit > a patch with all the proper procedure. I'm not sure if this is ok for YAMON-DT systems, will check on those systems. Thanks - Jiaxun > > Opinions welcome > > -dan > > > diff --git a/arch/mips/mti-malta/malta-setup.c b/arch/mips/mti-malta/malta-setup.c > index 21cb3ac1237b..52e731f9b4e2 100644 > --- a/arch/mips/mti-malta/malta-setup.c > +++ b/arch/mips/mti-malta/malta-setup.c > @@ -192,7 +192,9 @@ static void __init bonito_quirks_setup(void) > > void __init *plat_get_fdt(void) > { > - return (void *)__dtb_start; > + return (fw_arg0 == -2) ? > + (void *) (KSEG1ADDR(fw_arg1)) : > + (void *) __dtb_start; > } > > void __init plat_mem_setup(void) >
在2023年12月25日十二月 下午1:33，Jiaxun Yang写道： > 在 2023/12/22 17:51, dan@telent.net 写道: >> >> Newbie question: >> >> I noticed while writing some test automation with QEMU and U-Boot that >> the Malta kernel appears to ignore any DTB provided by the bootloader, in >> favour of using the one embedded into the kernel image. Is there a >> reason behind this, or is it just not a thing that's been changed since >> the board was converted to use device tree? > > Hi, > > It's a bit of history that DeviceTree passed by YAMON bootloader to > kernel does not compatible with upstream kernel's devicetree bindings, > so we decided to just omit it. Hi Dan, I checked malta YAMON firmware release and can confirm that it is safe on to do so. These firmwares won't set fw_arg0 to -2. I think you can make it a patch. Thanks - Jiaxun > >> >> I patched my own kernel to check $a1 as the "mips generic" kernel does, >> and it seems to work, but maybe I'm missing something? I did have to >> rebuild U-Boot with different CONFIG options to make use of it (I don't >> khow what real hardware Malta uses for a bootloader) so perhaps it has >> limited use. >> >> If the change is acceptable in principle I'll tidy it up and submit >> a patch with all the proper procedure. > > I'm not sure if this is ok for YAMON-DT systems, will check on those > systems. > > Thanks > - Jiaxun >> >> Opinions welcome >> >> -dan >> >> >> diff --git a/arch/mips/mti-malta/malta-setup.c b/arch/mips/mti-malta/malta-setup.c >> index 21cb3ac1237b..52e731f9b4e2 100644 >> --- a/arch/mips/mti-malta/malta-setup.c >> +++ b/arch/mips/mti-malta/malta-setup.c >> @@ -192,7 +192,9 @@ static void __init bonito_quirks_setup(void) >> >> void __init *plat_get_fdt(void) >> { >> - return (void *)__dtb_start; >> + return (fw_arg0 == -2) ? >> + (void *) (KSEG1ADDR(fw_arg1)) : >> + (void *) __dtb_start; >> } >> >> void __init plat_mem_setup(void) >>
diff --git a/arch/mips/mti-malta/malta-setup.c b/arch/mips/mti-malta/malta-setup.c index 21cb3ac1237b..52e731f9b4e2 100644 --- a/arch/mips/mti-malta/malta-setup.c +++ b/arch/mips/mti-malta/malta-setup.c @@ -192,7 +192,9 @@ static void __init bonito_quirks_setup(void) void __init *plat_get_fdt(void) { - return (void *)__dtb_start; + return (fw_arg0 == -2) ? + (void *) (KSEG1ADDR(fw_arg1)) : + (void *) __dtb_start; } void __init plat_mem_setup(void)