QEMU NUMA and U-Boot

[AKASHI Takahiro]

François,

On Tue, Jul 06, 2021 at 08:10:08PM +0200, Heinrich Schuchardt wrote:
> On 7/6/21 6:13 PM, François Ozog wrote:
> > Hi Heinrich, U-Boot 2021-07rc5 does not take into account memory
> > description when using Qemu 5.2 NUMA configuration to adapt memory map
> > (kernel_addr_r...):
> > 
> >         -smp 4 \
> >           -m 8G,slots=2,maxmem=16G \
> >          -object memory-backend-ram,size=4G,id=m0 \
> >          -object memory-backend-ram,size=4G,id=m1 \
> >          -numa node,cpus=0-1,nodeid=0,memdev=m0 \
> >          -numa node,cpus=2-3,nodeid=1,memdev=m1
> > 
> > kernel_addr_r is still 0x4040000 and thus you can't use it to bootefi.
> > 
> > fdt addr 0x13ede6de0; fdt print
> > 
> > Displays fdt while I think it should not.
> > 
> > If I load the kernel at dram.start, the load works but not boot
> > 
> > U-Boot 2021.07 (Jul 06 2021 - 13:26:43 +0000)
> > 
> > 
> > DRAM:4 GiB
> > 
> > Flash: 64 MiB
> > 
> > Loading Environment from Flash... OK
> > 
> > In:pl011 at 9000000
> > 
> > Out: pl011 at 9000000
> > 
> > Err: pl011 at 9000000
> > 
> > Net: eth0: virtio-net#32
> > 
> > Hit any key to stop autoboot:0
> > 
> > =>
> > 
> > => bdinfo
> > 
> > boot_params = 0x0000000000000000
> > 
> > DRAM bank = 0x0000000000000000
> > 
> > -> start= 0x0000000140000000
> > 
> > -> size = 0x0000000100000000
> > 
> > flashstart= 0x0000000000000000
> > 
> > flashsize = 0x0000000004000000
> > 
> > flashoffset = 0x00000000000bc990
> > 
> > baudrate= 115200 bps
> > 
> > relocaddr = 0x000000013ff27000
> > 
> > reloc off = 0x000000013ff27000
> > 
> > Build = 64-bit
> > 
> > current eth = virtio-net#32
> > 
> > ethaddr = 52:52:52:52:52:52
> > 
> > IP addr = <NULL>
> > 
> > fdt_blob= 0x000000013ede6de0
> > 
> > new_fdt = 0x000000013ede6de0
> > 
> > fdt_size= 0x0000000000100000
> > 
> > lmb_dump_all:
> > 
> > memory.cnt= 0x1
> > 
> > memory.reg[0x0].base = 0x140000000
> > 
> > .size = 0x100000000
> > 
> > 
> > reserved.cnt= 0x0
> > 
> > arch_number = 0x0000000000000000
> > 
> > TLB addr= 0x000000013fff0000
> > 
> > irq_sp= 0x000000013ede6dd0
> > 
> > sp start= 0x000000013ede6dd0
> > 
> > Early malloc usage: 3a8 / 2000
> > 
> > => load virtio 0:1 0x140000000 /oskit.efi
> > 
> > 853424 bytes read in 1 ms (813.9 MiB/s)
> > 
> > => bootefi0x140000000 0x13ede6dd0
> > 
> > ERROR: Failed to register WaitForKey event
> > 
> > Setting OsIndications failed
> > 
> > Error: Cannot initialize UEFI sub-system, r = 9
> > 
> > 
> > I think there is a need to calculate memory map based on previous
> > firmware (TFA, QEMU can be considered as previous frimware) information
> > (DT or blob_list).
> > 
> > What do you think ?
> > 
> > Cheers
> > 
> > FF
> > 
> > --
> > 
> > François-Frédéric Ozog | /Director Business Development/
> > T: +33.67221.6485
> > francois.ozog at linaro.org <mailto:francois.ozog at linaro.org> | Skype: ffozog
> > 
> > 
> 
> The kernel load address is hard coded here:
> include/configs/qemu-arm.h:41:  "kernel_addr_r=0x40400000\0" \
> 
> bdinfo shows:
> DRAM start = 0x140000000
> DRAM size  = 0x100000000
> 
> fdt addr $fdt_addr
> fdt printf
> 
> shows two memory areas. One at 40000000, one at 140000000.

(This shows that U-Boot receives a correct memory map via dtb.)

Is this a NUMA machine, isn't it? Why should we care of which
memory region be used here? Please note that this is a virtual machine,
there is no practical difference between two regions.

The root problem is that U-Boot did not recognize there were two
memory regions. We can fix this issue in either way:

1)
diff --git a/configs/qemu_arm64_defconfig b/configs/qemu_arm64_defconfig
index f6e586627a8e..b70ffae8bf6e 100644
--- a/configs/qemu_arm64_defconfig
+++ b/configs/qemu_arm64_defconfig
@@ -1,7 +1,7 @@
 CONFIG_ARM=y
 CONFIG_POSITION_INDEPENDENT=y
 CONFIG_ARCH_QEMU=y
-CONFIG_NR_DRAM_BANKS=1
+CONFIG_NR_DRAM_BANKS=2
 CONFIG_ENV_SIZE=0x40000
 CONFIG_ENV_SECT_SIZE=0x40000
 CONFIG_AHCI=y

2)
diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index 4b097fb588ed..4067ea2dead6 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -1111,7 +1111,7 @@ int fdtdec_setup_memory_banksize(void)
                return -EINVAL;
        }
 
-       for (bank = 0; bank < CONFIG_NR_DRAM_BANKS; bank++) {
+       for (bank = 0; ; bank++) {
                ret = ofnode_read_resource(mem, reg++, &res);
                if (ret < 0) {
                        reg = 0;

   (fdtdec_setup_memory_banksize() is called in dram_init_banksize().)


(2) seems much better, but I don't know why we had to use
CONFIG_NR_DRAM_BANKS here.

In this case, other occurrences of CONFIG_NR_DRAM_BANKS in this file
should be replaced with a variable for it. 

> Your use case is well beyond the typical U-Boot usage. So I guess it
> will be up to Linaro to provide the necessary patches:
> 
> * determine the active CPU
> * determine the RAM assigned to the active CPU according
>   to the numa-node-id in the device-tree
> * make sure that U-Boot only uses the memory of the active CPU
>   internally
> * make sure that the UEFI memory map contains a compliant description
> * possibly, dynamically set up the environment variables
> 
> +CC Tuomas Tynkkynen (maintainer for qemu_arm64_defconfig)

For (1), we'd better have a different config, or increase
the value of CONFIG_NR_DRAM_BANKS to a bigger number?

-Takahiro Akashi


> Best regards
> 
> Heinrich