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    SubjectRe: arch/x86/entry/entry: RFC on recent kernels building error with llvm 11.0.2 internal assembler
    On Mon, May 9, 2022 at 2:07 AM Nathan Chancellor <nathan@kernel.org> wrote:
    >
    > On Sat, May 07, 2022 at 02:19:00PM +0200, Mauro Rossi wrote:
    > > > > Alternatively, you could apply the hack that Nick inserted into Android
    > > > > for this issue if upgrading your toolchain or turning off the integrated
    > > > > assembler is not possible:
    > > > >
    > > > > https://android.googlesource.com/kernel/common/+/e58f084735b8abf744d61083b92172ee23d45aae
    > > > >
    > > > > I really do not mean to sound dismissive or rude, I apologize if it
    > > > > comes off that way, but we have worked quite hard to avoid inserting
    > > > > unnecessary workarounds, as they are ultimately technical debt that can
    > > > > be hard to manage over the long term.
    > > > >
    > > > > Cheers,
    > > > > Nathan
    > > >
    > > > Thanks a lot Nathan
    > > >
    > > > It is definitely the clang version 11.0.x which is not updated in aosp
    > > > Android 11 production tags
    > > >
    > > > I will use Nick's workaround which works since only lsl %rax, %rax is
    > > > currently happening
    > > >
    > > > Many thanks, problem solved
    > >
    > > Hello,
    > > I'm back again because I was assuming that Nick's workaround was working ok,
    > > but I have found that ARCH=x86_64 i.e. 64bit built kernel is causing
    > > an immediate hard reboot at initrd execution,
    > > just after hitting [ENTER] at grub/efi menu.
    >
    > It looks like there was a follow up fix for that workaround, maybe that
    > resolves this issue as well?
    >
    > https://android.googlesource.com/kernel/common/+/cc7f7a84191f5defc2ea4633eeea4acb4486b549
    >
    > > ARCh=x86 i.e. 32bit kernel binary is not affected, but is Nick's
    > > workaround targeting 32 bit kernel builds?
    >
    > No, the file that the build error originates from (entry_64.S) is only
    > built on x86_64.
    >
    > > How do aosp android-mailine kernels avoid this instantaneous hard reboot issue?
    >
    > That hack was reverted once the toolchain was upgraded:
    >
    > https://android.googlesource.com/kernel/common/+/ff0216d09fd31802537f2d1702ec2f3e9be73aa3
    > https://android.googlesource.com/kernel/common/+/3c2c8d8f7f2639e319212d10cb8df5bd13098dae
    >
    > Cheers,
    > Nathan

    Hello,

    sorry i still have the issue when building with hack "ANDROID: x86:
    entry: work around LLVM_IAS=1 bug in LSL"
    I'd just like to understand why I get instant reboot in 64bit kernel
    built with LLVM_IAS=1

    I searched for the places where #include "calling.h" is used

    utente@utente-3TB:~/r-x86_kernel/kernel$ grep -r \#include\ \"calling
    arch/x86/entry/thunk_64.S:#include "calling.h"
    arch/x86/entry/entry_32.S:#include "calling.h"
    arch/x86/entry/entry_64_compat.S:#include "calling.h"
    arch/x86/entry/entry_64.S:#include "calling.h"

    Probably the hardcoding done in the hack is impacting some other asm
    target built in 64 bit kernel and causes a wrong X86 instruction , is
    there a way to refine the #if defto avoid that problem while still
    building with LLVM_IAS=1 ?

    Thanks for the info
    Mauro

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