so, it is sort-of nack from David and sort-of ack from Segher, what happens now?
On 01/05/2019 13:42, Alexey Kardashevskiy wrote: > At the moment, on 256CPU + 256 PCI devices guest, it takes the guest > about 8.5sec to fetch the entire device tree via the client interface > as the DT is traversed twice - for strings blob and for struct blob. > Also, "getprop" is quite slow too as SLOF stores properties in a linked > list. > > However, since [1] SLOF builds flattened device tree (FDT) for another > purpose. [2] adds a new "fdt-fetch" client interface for the OS to fetch > the FDT. > > This tries the new method; if not supported, this falls back to > the old method. > > There is a change in the FDT layout - the old method produced > (reserved map, strings, structs), the new one receives only strings and > structs from the firmware and adds the final reserved map to the end, > so it is (fw reserved map, strings, structs, reserved map). > This still produces the same unflattened device tree. > > This merges the reserved map from the firmware into the kernel's reserved > map. At the moment SLOF generates an empty reserved map so this does not > change the existing behaviour in regard of reservations. > > This supports only v17 onward as only that version provides dt_struct_size > which works as "fdt-fetch" only produces v17 blobs. > > If "fdt-fetch" is not available, the old method of fetching the DT is used. > > [1] https://git.qemu.org/?p=SLOF.git;a=commitdiff;h=e6fc84652c9c00 > [2] https://git.qemu.org/?p=SLOF.git;a=commit;h=ecda95906930b80 > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> > --- > arch/powerpc/kernel/prom_init.c | 43 +++++++++++++++++++++++++++++++++ > 1 file changed, 43 insertions(+) > > diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c > index f33ff4163a51..72e7a602b68e 100644 > --- a/arch/powerpc/kernel/prom_init.c > +++ b/arch/powerpc/kernel/prom_init.c > @@ -2457,6 +2457,48 @@ static void __init flatten_device_tree(void) > prom_panic("Can't allocate initial device-tree chunk\n"); > mem_end = mem_start + room; > > + hdr = (void *) mem_start; > + if (!call_prom_ret("fdt-fetch", 2, 1, NULL, mem_start, > + room - sizeof(mem_reserve_map)) && > + hdr->version >= 17) { > + u32 size; > + struct mem_map_entry *fwrmap; > + > + /* Fixup the boot cpuid */ > + hdr->boot_cpuid_phys = cpu_to_be32(prom.cpu); > + > + /* > + * Store the struct and strings addresses, mostly > + * for consistency, only dt_header_start actually matters later. > + */ > + dt_header_start = mem_start; > + dt_string_start = mem_start + be32_to_cpu(hdr->off_dt_strings); > + dt_string_end = dt_string_start + > + be32_to_cpu(hdr->dt_strings_size); > + dt_struct_start = mem_start + be32_to_cpu(hdr->off_dt_struct); > + dt_struct_end = dt_struct_start + > + be32_to_cpu(hdr->dt_struct_size); > + > + /* > + * Calculate the reserved map location (which we put > + * at the blob end) and update total size. > + */ > + fwrmap = (void *)(mem_start + be32_to_cpu(hdr->off_mem_rsvmap)); > + hdr->off_mem_rsvmap = hdr->totalsize; > + size = be32_to_cpu(hdr->totalsize); > + hdr->totalsize = cpu_to_be32(size + sizeof(mem_reserve_map)); > + > + /* Merge reserved map from firmware to ours */ > + for ( ; fwrmap->size; ++fwrmap) > + reserve_mem(be64_to_cpu(fwrmap->base), > + be64_to_cpu(fwrmap->size)); > + > + rsvmap = (u64 *)(mem_start + size); > + > + prom_debug("Fetched DTB: %d bytes to @%lx\n", size, mem_start); > + goto finalize_exit; > + } > + > /* Get root of tree */ > root = call_prom("peer", 1, 1, (phandle)0); > if (root == (phandle)0) > @@ -2504,6 +2546,7 @@ static void __init flatten_device_tree(void) > /* Version 16 is not backward compatible */ > hdr->last_comp_version = cpu_to_be32(0x10); > > +finalize_exit: > /* Copy the reserve map in */ > memcpy(rsvmap, mem_reserve_map, sizeof(mem_reserve_map)); > > -- Alexey
