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riscv: KEXEC_TYPE_MULTIKERNEL Image loader, placement in the grant, no purgatory #26
Description
Part of the RISC-V port.
arch/riscv/kernel/kexec_image.c already loads the Image format at any 2 MB-aligned physical address (kernel VA is fixed, PA is free, kernel_map.va_pa_offset computed at runtime). machine_kexec_file.c always loads purgatory and jumps through it.
- Add
KEXEC_TYPE_MULTIKERNELhandling: place Image and instance DTB inside the grant (instance->memory_regions), never in the running kernel's memory; skip purgatory (kexec_load_purgatory(),riscv_kernel_entrysymbol patching). image->start= Image load address (_startis offset 0);image->arch.fdt_addr= instance DTB. These feed thefence.istub.- Never call
machine_kexec()/riscv_kexec_relocatepaths; the current kernel keeps running. - No PoC cleaning needed (harts are coherent), but execute
fenceafter writing the image/DTB/ctrl block so the stores are ordered beforeHART_START. - Regenerate the DTB
/memorynodes on every exec, not at load (the grant can change between load and exec; see the x86 "grant shortfall" fix).
Activity
pro-utkarshM commentedon Aug 26, 2026
i’m taking this as part of the #23-#26 RISC-V lifecycle and loader series. i’ll coordinate with @nickolaev and stack the work on #22 once the architecture foundation is available.
multikernel: serialize instance resource changes
pro-utkarshM commentedon Nov 3, 2026
The refreshed #26 follow-up is published separately at
riscv/image-loader-submit-v44,tip
ec098e55e2a3799329918236033a0882cd561779.It remains one loader commit above the refreshed #23-#25 lifecycle stack and
keeps multikernel Image placement inside the grant with no purgatory execution
path. The exact tip completed a cold rv64 LLVM
vmlinux+Imagelink; Imageparser (14 checks) and prepare fixtures passed. Preserved QEMU evidence covers
load rejection/retry plus manifest/grant/placement failure and retry on Sv39
and Sv48.
I am not folding this into PR #39 or the ordinary/crash-kexec purgatory fix in
PR #43. I am also leaving the older experimental #26 branches intact. A
separate loader PR can be opened once the #39 prerequisite/review shape is
accepted.