Michael S. Tsirkin 于2023年1月30日周一 23:07写道：
>
> On Mon, Jan 30, 2023 at 10:47:25PM +0800, Feng Sun wrote:
> > Igor Mammedov 于2023年1月24日周二 18:30写道：
> > >
> > > On Tue, 17 Jan 2023 19:15:21 +0800
> > > Sun Feng wrote:
> > >
> > > > Migrate from aarch64 host with PAGE_SIZE 64k to 4k failed with
> > > > following errors:
> > > >
> > > > qmp_cmd_name: migrate-incoming, arguments: {"uri": "tcp:[::]:49152"}
> > > > {"timestamp": {"seconds": 1673922775, "microseconds": 534702}, "event":
> > > > "MIGRATION", "data": {"status": "setup"}}
> > > > {"timestamp": {"seconds": 1673922776, "microseconds": 53003}, "event":
> > > > "MIGRATION", "data": {"status": "active"}}
> > > > 2023-01-17T02:32:56.058827Z qemu-system-aarch64: Length too large:
> > > > /rom@etc/acpi/rsdp: 0x1 > 0x1000: Invalid argument
> > >
> > > this should mention/explain why it's happening.
> > >
> > > i.e we now have 4k limit for RSDP, but then source somehow managed to
> > > start with 64k
> > > allocated to for RSDP. It looks like limit isn't working as expected to
> > > me.
> >
> > 4k limit should be romsize limit. I can see Rom '/rom@etc/acpi/rsdp'
> > with romsize:4096, datasize:36.
> > RAMBlock's used_length is set with datasize aligned to PAGE_SIZE, so
> > it become 64k when PAGE_SIZE is 64k.
> > ```
> > static
> > RAMBlock *qemu_ram_alloc_internal(ram_addr_t size, ram_addr_t max_size,
> > void (*resized)(const char*,
> > uint64_t length,
> > void *host),
> > void *host, uint32_t ram_flags,
> > MemoryRegion *mr, Error **errp)
> > {
> > RAMBlock *new_block;
> > Error *local_err = NULL;
> >
> > assert((ram_flags & ~(RAM_SHARED | RAM_RESIZEABLE | RAM_PREALLOC |
> > RAM_NORESERVE)) == 0);
> > assert(!host ^ (ram_flags & RAM_PREALLOC));
> >
> > size = HOST_PAGE_ALIGN(size);
> > max_size = HOST_PAGE_ALIGN(max_size);
> > new_block = g_malloc0(sizeof(*new_block));
> > new_block->mr = mr;
> > new_block->resized = resized;
> > new_block->used_length = size;
> > ```
> > So when migrate to 4k PAGE_SIZE, it will report the errors.
> >
> > ramblock information for PAGE_SIZE 64k and 4k.
> > ```
> > # getconf PAGE_SIZE
> > 65536
> > # virsh qemu-monitor-command testvm --hmp 'info ramblock'
> > Block NamePSize Offset
> > Used Total
> >mach-virt.ram 64 KiB 0x
> > 0x4000 0x4000
> > virt.flash0 64 KiB 0x4000
> > 0x0400 0x0400
> > virt.flash1 64 KiB 0x4400
> > 0x0400 0x0400
> > /rom@etc/acpi/tables 64 KiB 0x4804
> > 0x0002 0x0020
> > :00:01.2:00.0/virtio-net-pci.rom 64 KiB 0x4800
> > 0x0004 0x0004
> >/rom@etc/table-loader 64 KiB 0x4824
> > 0x0001 0x0001
> > /rom@etc/acpi/rsdp 64 KiB 0x4828
> > 0x0001 0x0001
> >
> > # getconf PAGE_SIZE
> > 4096
> > # virsh qemu-monitor-command testvm --hmp 'info ramblock'
> > Block NamePSize Offset
> > Used Total
> >mach-virt.ram4 KiB 0x
> > 0x0008 0x0008
> > virt.flash04 KiB 0x0008
> > 0x0400 0x0400
> > virt.flash14 KiB 0x00080400
> > 0x0400 0x0400
> > /rom@etc/acpi/tables4 KiB 0x00080800
> > 0x0002 0x0020
> >/rom@etc/table-loader4 KiB 0x00080820
> > 0x1000 0x0001
> > /rom@etc/acpi/rsdp4 KiB 0x00080824
> > 0x1000 0x1000
> > ```
>
> Oh interesting. I don't remember why I decided to align in.
> What does the followi
