Re: [RFC PATCH v1 00/57] Boot-time page size selection for arm64

Ryan Roberts
2024-10-24T11:02:59Z

On 23/10/2024 22:00, Thomas Tai wrote:
>
> On 10/17/2024 8:32 AM, Ryan Roberts wrote:
>> On 17/10/2024 13:27, Petr Tesarik wrote:
>>> On Mon, 14 Oct 2024 11:55:11 +0100
>>> Ryan Roberts <ryan.roberts@arm.com> wrote:
>>>
>>>> [...]
>>>> The series is arranged as follows:
>>>>
>>>>    - patch 1:       Add macros required for converting non-arch code to support
>>>>               boot-time page size selection
>>>>    - patches 2-36:  Remove PAGE_SIZE compile-time constant assumption from all
>>>>               non-arch code
>>> I have just tried to recompile the openSUSE kernel with these patches
>>> applied, and I'm running into this:
>>>
>>>    CC      arch/arm64/hyperv/hv_core.o
>>> In file included from ../arch/arm64/hyperv/hv_core.c:14:0:
>>> ../include/linux/hyperv.h:158:5: error: variably modified ‘reserved2’ at file
>>> scope
>>>    u8 reserved2[PAGE_SIZE - 68];
>>>       ^~~~~~~~~
>>>
>>> It looks like one more place which needs a patch, right?
>> As mentioned in the cover letter, so far I've only converted enough to get the
>> defconfig *image* building (i.e. no modules). If you are compiling a different
>> config or compiling the modules for defconfig, you will likely run into these
>> types of issues.
>
> It would be nice if you could provide the defconfig you are using; I also ran
> into build issues when using the arch/arm64/configs/defconfig.

git clean -xdfq
make defconfig

# Set CONFIG_ARM64_BOOT_TIME_PAGE_SIZE
./scripts/config --disable CONFIG_ARM64_4K_PAGES
./scripts/config --disable CONFIG_ARM64_16K_PAGES
./scripts/config --disable CONFIG_ARM64_64K_PAGES
./scripts/config --disable CONFIG_ARM64_BOOT_TIME_PAGE_SIZE
./scripts/config --enable CONFIG_ARM64_BOOT_TIME_PAGE_SIZE

# Set ARM64_VA_BITS_48
./scripts/config --disable ARM64_VA_BITS_36
./scripts/config --disable ARM64_VA_BITS_39
./scripts/config --disable ARM64_VA_BITS_42
./scripts/config --disable ARM64_VA_BITS_47
./scripts/config --disable ARM64_VA_BITS_48
./scripts/config --disable ARM64_VA_BITS_52
./scripts/config --enable ARM64_VA_BITS_48

# Optional: filesystems known to compile with boot-time page size
./scripts/config --enable CONFIG_SQUASHFS_LZ4
./scripts/config --enable CONFIG_SQUASHFS_LZO
./scripts/config --enable CONFIG_SQUASHFS_XZ
./scripts/config --enable CONFIG_SQUASHFS_ZSTD
./scripts/config --enable CONFIG_XFS_FS

# Optional: trace stuff known to compile with boot-time page size
./scripts/config --enable CONFIG_FTRACE
./scripts/config --enable CONFIG_FUNCTION_TRACER
./scripts/config --enable CONFIG_KPROBES
./scripts/config --enable CONFIG_HIST_TRIGGERS
./scripts/config --enable CONFIG_FTRACE_SYSCALLS

# Optional: misc mm stuff known to compile with boot-time page size
./scripts/config --enable CONFIG_PTDUMP_DEBUGFS
./scripts/config --enable CONFIG_READ_ONLY_THP_FOR_FS
./scripts/config --enable CONFIG_USERFAULTFD

# Optional: mm debug stuff known compile with boot-time page size
./scripts/config --enable CONFIG_DEBUG_VM
./scripts/config --enable CONFIG_DEBUG_VM_MAPLE_TREE
./scripts/config --enable CONFIG_DEBUG_VM_RB
./scripts/config --enable CONFIG_DEBUG_VM_PGFLAGS
./scripts/config --enable CONFIG_DEBUG_VM_PGTABLE
./scripts/config --enable CONFIG_PAGE_TABLE_CHECK
./scripts/config --enable CONFIG_PAGE_TABLE_CHECK_ENFORCED

make olddefconfig
make -s -j`nproc` Image

So I'm explicitly only building and booting the kernel image, not the modules.
The kernel image contains all the drivers needed to get a VM up and running
under QEMU/KVM.

Thanks,
Ryan

>
> Thank you,
> Thomas
>
>>
>> That said, I do have some patches to fix Hyper-V, which Michael Kelley was kind
>> enough to send me.
>>
>> I understand that Suse might be able to help with wider performance testing - if
>> that's the reason you are trying to compile, you could send me your config and
>> I'll start working on fixing up other drivers?
>>
>> Thanks,
>> Ryan
>>
>>> Petr T
>>