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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Minios-devel] [PATCH 00/40] MINI-OS: enable the arm64 support
Hi Shijie,First of all, I think this should be tagged with RFC as the code is not in shape to get merged (more details below). Before speaking about this series itself, I think it is important to mention the state of the arm32 port. Putting aside the fact it does not compile, it also has quite a few shortcoming. To name a few:
1) Use of short-descriptor page tables
2) No support for SMP
3) No coherence in the coding style
4) Functions left unimplemented (e.g arch_pfn_add, allocat_ondemand)
5) Devices mapped using memory attribute. It relies on the hypervisor
to tighten attributes.
6) Assumption of the VM layout which is not part of the ABI. Such as
event IRQ and timer IRQ number and their configuration (i.e
level-sensitive/edge-triggered).
7) Assumption on the way DT has been created
8) GICv2 driver no compliant with the spec
I could probably list more... but I think the list is enough to make my
point. The current code for Arm in Mini-OS is currently not in shape.
5-8 are the most critical ones as it implies that Mini-OS does not follow the ABI and the architecture. This may get broken for any change in the hypervisor and potentially in the hardware. Now, this series is adding arm64 port in the same directory, despite the fact the design chosen is fairly different. This is noticeable by the amount of #ifdef arm64 within the code. Furthermore, if you re-use the same directory. I would have expected some preparatory patches to move arm32 specific code under in sub-directory. I am quite surprised this is not present in the diff below. Overall, it feels there are a lack of cohesion between the Arm32 and Arm64 ports. This is surprising given that AFAIK the difference between arm32 and arm64 should be fairly limited in the context of Mini-OS. It is basically done to:
- boot code
- exception entry/exit
- registers naming
- system registers access (arm64) vs co-processors (arm32) access
Regarding page-tables, ARMv7 support both short-descriptor and LPAE. The
latter is not optional when the processor provides virtual extensions.
Arm64 only support LPAE format, if the Arm32 port is switch to LPAE code
handling page-table could be shared here.
I can see two solutions going forward:
1) The arm directory is first reshaped to welcome arm64. This means:
* moving out arm32 specific code
* switch to LPAE page-table
* introducing helpers for common code to call arch-specific code
On the code is reshaped, the arm64 series is added on top.
2) Start the arm64 port from a clean slate and then port arm32 over.
Knowing the state of the arm32 port, I would lean towards 2). This would
allow more flexibility and make easier to review. At the moment, I have
to hunt down the code to see what is missing.
I would be interested to hear the opinion of the maintainers here. Cheers, On 03/11/17 03:11, Huang Shijie wrote: The work is based on Chen Baozi and Volodymyr's patches. I tested this patch set with my Softiron board. This patch set is based on the latest mini-os code: (git tree: https://github.com/lorc/mini-os.git The top is " 0b4b789 Update Xen header files again") After this patch set: 1.) The scheduler for arm64 works fine. 2.) The gic/timer for arm64 works fine. I tested this patch set on Softiron(arm64) and x86_64 platform. Please see the log after the patch set: --------------------------------------------------------- (d1) - Mini-OS booting - (d1) - Setup CPU - (d1) - Setup booting pagetable - (d1) - MMU on - (d1) - Setup stack - (d1) - Jumping to C entry - (d1) Virtual -> physical offset = ffffffbfc0000000 (d1) Checking DTB at 0xffffffc008000000... (d1) MM: Init (d1) _text: 0xffffffc000000000(VA) (d1) _etext: 0xffffffc000019a0c(VA) (d1) _erodata: 0xffffffc000020000(VA) (d1) _edata: 0xffffffc00002a38c(VA) (d1) stack start: 0xffffffc000026000(VA) (d1) _end: 0xffffffc0000337a0(VA) (d1) Found memory at 0x40000000 (len 0x20000000) (d1) Using pages 262196 to 393216 as free space for heap. (d1) MM: Initialise page allocator for ffffffc000034000(40034000)-ffffffc01ffff000(5ffff000) (d1) Adding memory range 40040000-5ffff000 (d1) MM: done (d1) Found GIC: gicd_base = 0xffffffbfc3001000, gicc_base = 0xffffffbfc3002000 (d1) Initialising timer interface (d1) Virtual Count register is 2abcb3e, freq = 250000000 Hz (d1) Initialising console ... done. (d1) FDT suggests grant table base 38000000 (d1) gnttab_table mapped at 0xffffffbff8000000. (d1) Initialising scheduler (d1) Thread "Idle": pointer: 0x0xffffffc01fff8078, stack: 0x0xffffffc01fff0000 (d1) Thread "xenstore": pointer: 0x0xffffffc01fff80d8, stack: 0x0xffffffc01fff4000 (d1) xenbus initialised on irq 1 (d1) Thread "shutdown": pointer: 0x0xffffffc01fff8138, stack: 0x0xffffffc01ffe0000 (d1) kernel.c: dummy main: par=0 --------------------------------------------------------- Huang Shijie (40): mini-os: fix the wrong parameter for map_free() in init_page_allocator() mini-os: replace the L1_PAGETABLE_SHIFT with PAGE_SHIFT arm64: add the boot code arm64: change physical_address_offset to paddr_t arm64: fix the wrong mask for to_virt/to_phys arm64: add the __PAGE_SIZE macro in header file arm64: add exception support arm64: dump the registers for do_bad_mode()/do_sync() arm64: add the basic helpers for arm64 arm64: define the quad_t for arm64 arm64: time.c: fix the wrong format for printk mini-os: define ULONG_MAX/LONG_MAX for arm64 mini-os: remove the e820 from common code arm64: mm.c: fix the compiler error arm64: refine the arch_init_mm arm64: add shared_info support mini-os: implement the memmove/memchr mini-os: fix the compilor error in time arm64: define the CALLEE_SAVED_REGISTERS arm64: implement the __arch_switch_threads arm64: implement the arm_start_thread arm64: change sp to "unsigned long" type arm64: fix the wrong size of the register arm64: implement the run_idle_thread arm64: set the stack for the arm_start_thread mini-os: update the .gitignore arm64: add the header file arch_wordsize.h arm64: add the hypercall support arm64: init the memory system before console/xenbus/gic arm64: set the mapping for console and xenbus arm: add a new helper ioremap arm: parse out the address/size for gicd/gicc arm64: gic: implement the REG_WRITE32/REG_READ32 arm64: implement the timer helpers for arm64 arm64: time.c: read out the frequency for arm64 arm64: add the link file arm64: add the makefile mini-os: Set TARGET_ARCH_FAM for arm64 mini-os: create the image for arm mini-os: compile the dtc submodule for arm64 .gitignore | 4 + .gitmodules | 3 + Config.mk | 11 +- Makefile | 23 ++ arch/arm/arm64/Makefile | 26 ++ arch/arm/arm64/arch.mk | 7 + arch/arm/arm64/arm64.S | 534 ++++++++++++++++++++++++++++++++++++++ arch/arm/arm64/asm.h | 18 ++ arch/arm/arm64/hypercalls64.S | 81 ++++++ arch/arm/arm64/minios-arm64.lds.S | 76 ++++++ arch/arm/arm64/traps.c | 44 ++++ arch/arm/gic.c | 81 +++++- arch/arm/mm.c | 216 +++++++++++++-- arch/arm/sched.c | 34 ++- arch/arm/setup.c | 10 +- arch/arm/time.c | 21 +- arch/x86/mm.c | 17 +- include/arm/arch_limits.h | 2 + include/arm/arch_mm.h | 26 +- include/arm/arm32/os.h | 32 +++ include/arm/arm64/arch_wordsize.h | 7 + include/arm/arm64/os.h | 41 +++ include/arm/arm64/pagetable.h | 106 ++++++++ include/arm/os.h | 65 +---- include/arm/traps.h | 14 + include/mm.h | 3 + include/posix/limits.h | 2 +- include/sys/time.h | 4 + include/types.h | 2 +- lib/memmove.c | 44 ++++ lib/string.c | 12 + mm.c | 15 +- 32 files changed, 1451 insertions(+), 130 deletions(-) create mode 100644 .gitmodules create mode 100644 arch/arm/arm64/Makefile create mode 100644 arch/arm/arm64/arch.mk create mode 100644 arch/arm/arm64/arm64.S create mode 100644 arch/arm/arm64/asm.h create mode 100644 arch/arm/arm64/hypercalls64.S create mode 100644 arch/arm/arm64/minios-arm64.lds.S create mode 100644 arch/arm/arm64/traps.c create mode 100644 include/arm/arm32/os.h create mode 100644 include/arm/arm64/arch_wordsize.h create mode 100644 include/arm/arm64/os.h create mode 100644 include/arm/arm64/pagetable.h create mode 100644 lib/memmove.c -- Julien Grall _______________________________________________ Minios-devel mailing list Minios-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/cgi-bin/mailman/listinfo/minios-devel
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