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Kernel boot time #160
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The SPI read timing calibration takes some cycles :
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The time spent in populate_rootfs is the time taken to unpack the compressed initramfs file system. The compression method was chosen to minimize the on-flash size. Other options may require less time to unpack. Converting the shell script to C would be another alternative (some would probably like the elimination of the shell), and the dedicated binary should take a lot less space than the full busybox binary without sacrificing function. (The development features could then be compiled out). As a less drastic option, one could try to minimize the busybox config to only include the commands used by the init, update, and reboot scripts. We could explore static linking (eg we don't need external mtd tools for ubi commands). Another thought is to eliminate the need for the initramfs stage by directly mounting the squashfs root file system from the mtd similar to what we do with witherspoon and the ubi-fs option. This would require splitting out the feature into "mostly-readonly just var and etc in the overlayfs" from the ubi-fs distro feature, and then finding an alternative method for prepare-to-update-flash to run from ram. If we go back and enable the ramdisk block devices we could just load the root squashfs mtd partition as the initramfs and mount it using root=/dev/ram0 for update mode (although the kernel would end up copying the data 3 times, it would not involve decompression). |
[ Upstream commit 0f20615 ] Fix BPF_CORE_READ_BITFIELD() macro used for reading CO-RE-relocatable bitfields. Missing breaks in a switch caused 8-byte reads always. This can confuse libbpf because it does strict checks that memory load size corresponds to the original size of the field, which in this case quite often would be wrong. After fixing that, we run into another problem, which quite subtle, so worth documenting here. The issue is in Clang optimization and CO-RE relocation interactions. Without that asm volatile construct (also known as barrier_var()), Clang will re-order BYTE_OFFSET and BYTE_SIZE relocations and will apply BYTE_OFFSET 4 times for each switch case arm. This will result in the same error from libbpf about mismatch of memory load size and original field size. I.e., if we were reading u32, we'd still have *(u8 *), *(u16 *), *(u32 *), and *(u64 *) memory loads, three of which will fail. Using barrier_var() forces Clang to apply BYTE_OFFSET relocation first (and once) to calculate p, after which value of p is used without relocation in each of switch case arms, doing appropiately-sized memory load. Here's the list of relevant relocations and pieces of generated BPF code before and after this patch for test_core_reloc_bitfields_direct selftests. BEFORE ===== #45: core_reloc: insn #160 --> [5] + 0:5: byte_sz --> struct core_reloc_bitfields.u32 #46: core_reloc: insn #167 --> [5] + 0:5: byte_off --> struct core_reloc_bitfields.u32 #47: core_reloc: insn #174 --> [5] + 0:5: byte_off --> struct core_reloc_bitfields.u32 #48: core_reloc: insn #178 --> [5] + 0:5: byte_off --> struct core_reloc_bitfields.u32 #49: core_reloc: insn #182 --> [5] + 0:5: byte_off --> struct core_reloc_bitfields.u32 157: 18 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r2 = 0 ll 159: 7b 12 20 01 00 00 00 00 *(u64 *)(r2 + 288) = r1 160: b7 02 00 00 04 00 00 00 r2 = 4 ; BYTE_SIZE relocation here ^^^ 161: 66 02 07 00 03 00 00 00 if w2 s> 3 goto +7 <LBB0_63> 162: 16 02 0d 00 01 00 00 00 if w2 == 1 goto +13 <LBB0_65> 163: 16 02 01 00 02 00 00 00 if w2 == 2 goto +1 <LBB0_66> 164: 05 00 12 00 00 00 00 00 goto +18 <LBB0_69> 0000000000000528 <LBB0_66>: 165: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll 167: 69 11 08 00 00 00 00 00 r1 = *(u16 *)(r1 + 8) ; BYTE_OFFSET relo here w/ WRONG size ^^^^^^^^^^^^^^^^ 168: 05 00 0e 00 00 00 00 00 goto +14 <LBB0_69> 0000000000000548 <LBB0_63>: 169: 16 02 0a 00 04 00 00 00 if w2 == 4 goto +10 <LBB0_67> 170: 16 02 01 00 08 00 00 00 if w2 == 8 goto +1 <LBB0_68> 171: 05 00 0b 00 00 00 00 00 goto +11 <LBB0_69> 0000000000000560 <LBB0_68>: 172: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll 174: 79 11 08 00 00 00 00 00 r1 = *(u64 *)(r1 + 8) ; BYTE_OFFSET relo here w/ WRONG size ^^^^^^^^^^^^^^^^ 175: 05 00 07 00 00 00 00 00 goto +7 <LBB0_69> 0000000000000580 <LBB0_65>: 176: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll 178: 71 11 08 00 00 00 00 00 r1 = *(u8 *)(r1 + 8) ; BYTE_OFFSET relo here w/ WRONG size ^^^^^^^^^^^^^^^^ 179: 05 00 03 00 00 00 00 00 goto +3 <LBB0_69> 00000000000005a0 <LBB0_67>: 180: 18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll 182: 61 11 08 00 00 00 00 00 r1 = *(u32 *)(r1 + 8) ; BYTE_OFFSET relo here w/ RIGHT size ^^^^^^^^^^^^^^^^ 00000000000005b8 <LBB0_69>: 183: 67 01 00 00 20 00 00 00 r1 <<= 32 184: b7 02 00 00 00 00 00 00 r2 = 0 185: 16 02 02 00 00 00 00 00 if w2 == 0 goto +2 <LBB0_71> 186: c7 01 00 00 20 00 00 00 r1 s>>= 32 187: 05 00 01 00 00 00 00 00 goto +1 <LBB0_72> 00000000000005e0 <LBB0_71>: 188: 77 01 00 00 20 00 00 00 r1 >>= 32 AFTER ===== #30: core_reloc: insn #132 --> [5] + 0:5: byte_off --> struct core_reloc_bitfields.u32 #31: core_reloc: insn #134 --> [5] + 0:5: byte_sz --> struct core_reloc_bitfields.u32 129: 18 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r2 = 0 ll 131: 7b 12 20 01 00 00 00 00 *(u64 *)(r2 + 288) = r1 132: b7 01 00 00 08 00 00 00 r1 = 8 ; BYTE_OFFSET relo here ^^^ ; no size check for non-memory dereferencing instructions 133: 0f 12 00 00 00 00 00 00 r2 += r1 134: b7 03 00 00 04 00 00 00 r3 = 4 ; BYTE_SIZE relocation here ^^^ 135: 66 03 05 00 03 00 00 00 if w3 s> 3 goto +5 <LBB0_63> 136: 16 03 09 00 01 00 00 00 if w3 == 1 goto +9 <LBB0_65> 137: 16 03 01 00 02 00 00 00 if w3 == 2 goto +1 <LBB0_66> 138: 05 00 0a 00 00 00 00 00 goto +10 <LBB0_69> 0000000000000458 <LBB0_66>: 139: 69 21 00 00 00 00 00 00 r1 = *(u16 *)(r2 + 0) ; NO CO-RE relocation here ^^^^^^^^^^^^^^^^ 140: 05 00 08 00 00 00 00 00 goto +8 <LBB0_69> 0000000000000468 <LBB0_63>: 141: 16 03 06 00 04 00 00 00 if w3 == 4 goto +6 <LBB0_67> 142: 16 03 01 00 08 00 00 00 if w3 == 8 goto +1 <LBB0_68> 143: 05 00 05 00 00 00 00 00 goto +5 <LBB0_69> 0000000000000480 <LBB0_68>: 144: 79 21 00 00 00 00 00 00 r1 = *(u64 *)(r2 + 0) ; NO CO-RE relocation here ^^^^^^^^^^^^^^^^ 145: 05 00 03 00 00 00 00 00 goto +3 <LBB0_69> 0000000000000490 <LBB0_65>: 146: 71 21 00 00 00 00 00 00 r1 = *(u8 *)(r2 + 0) ; NO CO-RE relocation here ^^^^^^^^^^^^^^^^ 147: 05 00 01 00 00 00 00 00 goto +1 <LBB0_69> 00000000000004a0 <LBB0_67>: 148: 61 21 00 00 00 00 00 00 r1 = *(u32 *)(r2 + 0) ; NO CO-RE relocation here ^^^^^^^^^^^^^^^^ 00000000000004a8 <LBB0_69>: 149: 67 01 00 00 20 00 00 00 r1 <<= 32 150: b7 02 00 00 00 00 00 00 r2 = 0 151: 16 02 02 00 00 00 00 00 if w2 == 0 goto +2 <LBB0_71> 152: c7 01 00 00 20 00 00 00 r1 s>>= 32 153: 05 00 01 00 00 00 00 00 goto +1 <LBB0_72> 00000000000004d0 <LBB0_71>: 154: 77 01 00 00 20 00 00 00 r1 >>= 323 Fixes: ee26dad ("libbpf: Add support for relocatable bitfields") Signed-off-by: Andrii Nakryiko <[email protected]> Signed-off-by: Alexei Starovoitov <[email protected]> Acked-by: Lorenz Bauer <[email protected]> Link: https://lore.kernel.org/bpf/[email protected] Signed-off-by: Sasha Levin <[email protected]>
commit 1a0c016 upstream. Move am65_cpsw_nuss_phylink_cleanup() call to after am65_cpsw_nuss_cleanup_ndev() so phylink is still valid to prevent the below Segmentation fault on module remove when first slave link is up. [ 31.652944] Unable to handle kernel paging request at virtual address 00040008000005f4 [ 31.684627] Mem abort info: [ 31.687446] ESR = 0x0000000096000004 [ 31.704614] EC = 0x25: DABT (current EL), IL = 32 bits [ 31.720663] SET = 0, FnV = 0 [ 31.723729] EA = 0, S1PTW = 0 [ 31.740617] FSC = 0x04: level 0 translation fault [ 31.756624] Data abort info: [ 31.759508] ISV = 0, ISS = 0x00000004 [ 31.776705] CM = 0, WnR = 0 [ 31.779695] [00040008000005f4] address between user and kernel address ranges [ 31.808644] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP [ 31.814928] Modules linked in: wlcore_sdio wl18xx wlcore mac80211 libarc4 cfg80211 rfkill crct10dif_ce phy_gmii_sel ti_am65_cpsw_nuss(-) sch_fq_codel ipv6 [ 31.828776] CPU: 0 PID: 1026 Comm: modprobe Not tainted 6.1.0-rc2-00012-gfabfcf7dafdb-dirty #160 [ 31.837547] Hardware name: Texas Instruments AM625 (DT) [ 31.842760] pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 31.849709] pc : phy_stop+0x18/0xf8 [ 31.853202] lr : phylink_stop+0x38/0xf8 [ 31.857031] sp : ffff80000a0839f0 [ 31.860335] x29: ffff80000a0839f0 x28: ffff000000de1c80 x27: 0000000000000000 [ 31.867462] x26: 0000000000000000 x25: 0000000000000000 x24: ffff80000a083b98 [ 31.874589] x23: 0000000000000800 x22: 0000000000000001 x21: ffff000001bfba90 [ 31.881715] x20: ffff0000015ee000 x19: 0004000800000200 x18: 0000000000000000 [ 31.888842] x17: ffff800076c45000 x16: ffff800008004000 x15: 000058e39660b106 [ 31.895969] x14: 0000000000000144 x13: 0000000000000144 x12: 0000000000000000 [ 31.903095] x11: 000000000000275f x10: 00000000000009e0 x9 : ffff80000a0837d0 [ 31.910222] x8 : ffff000000de26c0 x7 : ffff00007fbd6540 x6 : ffff00007fbd64c0 [ 31.917349] x5 : ffff00007fbd0b10 x4 : ffff00007fbd0b10 x3 : ffff00007fbd3920 [ 31.924476] x2 : d0a07fcff8b8d500 x1 : 0000000000000000 x0 : 0004000800000200 [ 31.931603] Call trace: [ 31.934042] phy_stop+0x18/0xf8 [ 31.937177] phylink_stop+0x38/0xf8 [ 31.940657] am65_cpsw_nuss_ndo_slave_stop+0x28/0x1e0 [ti_am65_cpsw_nuss] [ 31.947452] __dev_close_many+0xa4/0x140 [ 31.951371] dev_close_many+0x84/0x128 [ 31.955115] unregister_netdevice_many+0x130/0x6d0 [ 31.959897] unregister_netdevice_queue+0x94/0xd8 [ 31.964591] unregister_netdev+0x24/0x38 [ 31.968504] am65_cpsw_nuss_cleanup_ndev.isra.0+0x48/0x70 [ti_am65_cpsw_nuss] [ 31.975637] am65_cpsw_nuss_remove+0x58/0xf8 [ti_am65_cpsw_nuss] Cc: <[email protected]> # v5.18+ Fixes: e8609e6 ("net: ethernet: ti: am65-cpsw: Convert to PHYLINK") Signed-off-by: Roger Quadros <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
The BMC kernel takes about 9 seconds to start on a Romulus machine. The three biggest chunks come from these init calls:
We should see if these can be reduced.
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