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baremetal aarch64: create C version of multicore.S as well

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Attempted to do the same for arm, but it failed.
This commit is contained in:
Ciro Santilli 六四事件 法轮功
2019-08-21 00:00:00 +00:00
parent 6f88fa17bc
commit f28191a735
21 changed files with 336 additions and 89 deletions
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39
README.adoc
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@@ -15470,15 +15470,23 @@ Semihosting is implemented both on some real devices and on simulators such as Q
It is documented at: https://developer.arm.com/docs/100863/latest/introduction
For example, the following code makes QEMU exit:
For example, all the following code make QEMU exit:
....
./run --arch arm --baremetal baremetal/arch/arm/semihost_exit.S
./run --arch arm --baremetal baremetal/arch/arm/no_bootloader/semihost_exit.S
./run --arch aarch64 --baremetal baremetal/arch/aarch64/semihost_exit.S
./run --arch aarch64 --baremetal baremetal/arch/aarch64/no_bootloader/semihost_exit.S
....
Source: link:baremetal/arch/arm/no_bootloader/semihost_exit.S[]
Sources:
That program program contains the code:
* link:baremetal/arch/arm/semihost_exit.S[]
* link:baremetal/arch/arm/no_bootloader/semihost_exit.S[]
* link:baremetal/arch/aarch64/semihost_exit.S[]
* link:baremetal/arch/aarch64/no_bootloader/semihost_exit.S[]
That `arm` program program contains the code:
....
mov r0, #0x18
@@ -16171,17 +16179,26 @@ See the example at: xref:arm-svc-instruction[xrefstyle=full]
==== ARM multicore
Examples:
....
./run --arch aarch64 --baremetal baremetal/arch/aarch64/multicore.S --cpus 2
./run --arch aarch64 --baremetal baremetal/arch/aarch64/multicore.S --cpus 2 --emulator gem5
./run --arch arm --baremetal baremetal/arch/aarch64/multicore.S --cpus 2
./run --arch arm --baremetal baremetal/arch/aarch64/multicore.S --cpus 2 --emulator gem5
./run --arch aarch64 --baremetal baremetal/arch/aarch64/no_bootloader/multicore_asm.S --cpus 2
./run --arch aarch64 --baremetal baremetal/arch/aarch64/no_bootloader/multicore_asm.S --cpus 2 --emulator gem5
./run --arch aarch64 --baremetal baremetal/arch/aarch64/multicore.c --cpus 2
./run --arch aarch64 --baremetal baremetal/arch/aarch64/multicore.c --cpus 2 --emulator gem5
./run --arch arm --baremetal baremetal/arch/arm/no_bootloader/multicore_asm.S --cpus 2
./run --arch arm --baremetal baremetal/arch/arm/no_bootloader/multicore_asm.S --cpus 2 --emulator gem5
# TODO not working, hangs.
# ./run --arch arm --baremetal baremetal/arch/arm/multicore.c --cpus 2
./run --arch arm --baremetal baremetal/arch/arm/multicore.c --cpus 2 --emulator gem5
....
Sources:
* link:baremetal/arch/aarch64/multicore.S[]
* link:baremetal/arch/arm/multicore.S[]
* link:baremetal/arch/aarch64/no_bootloader/multicore_asm.S[]
* link:baremetal/arch/aarch64/multicore.c[]
* link:baremetal/arch/arm/no_bootloader/multicore_asm.S[]
* link:baremetal/arch/arm/multicore.c[]
CPU 0 of this program enters a spinlock loop: it repeatedly checks if a given memory address is 1.
@@ -16190,7 +16207,7 @@ So, we need CPU 1 to come to the rescue and set that memory address to 1, otherw
Don't believe me? Then try:
....
./run --arch aarch64 --baremetal baremetal/arch/aarch64/multicore.S --cpus 1
./run --arch aarch64 --baremetal baremetal/arch/aarch64/multicore.c --cpus 1
....
and watch it hang forever.
@@ -16198,7 +16215,7 @@ and watch it hang forever.
Note that if you try the same thing on gem5:
....
./run --arch aarch64 --baremetal baremetal/arch/aarch64/multicore.S --cpus 1 --emulator gem5
./run --arch aarch64 --baremetal baremetal/arch/aarch64/multicore.c --cpus 1 --emulator gem5
....
then the gem5 actually exits with <<gem5-simulate-limit-reached>> as opposed to the expected: