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Re: [Minios-devel] [PATCH 00/47] MINI-OS: enable the arm64 support



Hi Shijie,

Few generic comments on this series.

On 03/14/2018 09:39 AM, Huang Shijie wrote:
  2.) Tests
    I tested this patch set on Softiron(arm64) and x86_64 platform.

How about arm32? What is the state after this series?

On the previous version, I clearly suggested 2 paths to add support for arm64:

"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."

This series does not follow any of them and end up to have #if defined(__aarch64__) in the common code. This really defeating the purpose of the refactoring below.

To be clear, I am not suggesting to add arm32 port, I am just asking to not make things worst than the current state.

   4.) The comments from Julien which I did not follow:
      0) Use p2m_set_entry to setup the page table.
         I did not have good understanding of the p2m_set_entry().
        So I use my familiar way to setup the page table.

I haven't seen any discussion from you since November about misunderstanding in my suggestions...


      1) Move dsb/dmb/mb to common place.
         I did not do so, because I found the older arm32 archs
         use "mcr" to do the memory barriers.

Hu? B4.2.5 in ARM DDI  0406C.c says:

"In ARMv7, ARM deprecates any use of these CP15 c7 operations, and strongly recommends that software uses the ISB , DSB , and DMB instructions instead."

Mini-OS will always run on ARMv7 or later architecture.
        
Cheers,

--
Julien Grall

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