On 10.06.2025 19:39, Jason Andryuk wrote: > > > On 2025-06-10 02:56, Jan Beulich wrote: >> On 09.06.2025 19:07, Jason Andryuk wrote: >>> On 2025-04-29 08:36, Alejandro Vallejo wrote: >>>> From: "Daniel P. Smith" <dpsm...@apertussolutions.com> >>>> >>>> Add support to read the command line from the hyperlaunch device tree. >>>> The device tree command line is located in the "bootargs" property of the >>>> "multiboot,kernel" node. >>>> >>>> A boot loader command line, e.g. a grub module string field, takes >>>> precendence over the device tree one since it is easier to modify. >>>> >>>> Signed-off-by: Daniel P. Smith <dpsm...@apertussolutions.com> >>>> Signed-off-by: Jason Andryuk <jason.andr...@amd.com> >>>> Signed-off-by: Alejandro Vallejo <agarc...@amd.com> >>>> Reviewed-by: Denis Mukhin <dmuk...@ford.com> >>>> --- >>> >>>> diff --git a/xen/common/domain-builder/fdt.c >>>> b/xen/common/domain-builder/fdt.c >>>> index cbb0ed30a2..dabe201b04 100644 >>>> --- a/xen/common/domain-builder/fdt.c >>>> +++ b/xen/common/domain-builder/fdt.c >>>> @@ -219,6 +219,12 @@ static int __init fdt_process_domain_node( >>>> printk(XENLOG_INFO " kernel: multiboot-index=%d\n", idx); >>>> bi->mods[idx].type = BOOTMOD_KERNEL; >>>> bd->kernel = &bi->mods[idx]; >>>> + >>>> + /* If bootloader didn't set cmdline, see if FDT provides one. >>>> */ >>>> + if ( bd->kernel->cmdline_pa && >>>> + !((char *)__va(bd->kernel->cmdline_pa))[0] ) >>> >>> The logic is incorrect - it should be: >>> >>> if ( !bd->kernel->cmdline_pa || >>> !((char *)__va(bd->kernel->cmdline_pa))[0] ) >>> >>> If there is no cmdline_pa (which happens with the "reg" property) or the if >>> there is a 0-length string, then check the DT for bootargs. >> >> Even that sounds bogus to me: There's a difference between "no command line" >> and "empty command line". > > Yes, you have a point. The difficulty is grub always provides a NUL > terminated string, so Xen can't differentiate the two.
Which may call for either special-casing GrUB, or at least calling out that behavior in the comment. (Ideally we'd still have a way to distinguish between both cases, but likely we'll need to resort to documenting that some dummy option will need adding to tell "none" from [intended to be] empty.) Jan
