• Geert Uytterhoeven's avatar
    um: Preinclude include/linux/kern_levels.h · 9429ec96
    Geert Uytterhoeven authored
    The userspace part of UML uses the asm-offsets.h generator mechanism to
    create definitions for UM_KERN_<LEVEL> that match the in-kernel
    KERN_<LEVEL> constant definitions.
    
    As of commit 04d2c8c8 ("printk: convert
    the format for KERN_<LEVEL> to a 2 byte pattern"), KERN_<LEVEL> is no
    longer expanded to the literal '"<LEVEL>"', but to '"\001" "LEVEL"', i.e.
    it contains two parts.
    
    However, the combo of DEFINE_STR() in
    arch/x86/um/shared/sysdep/kernel-offsets.h and sed-y in Kbuild doesn't
    support string literals consisting of multiple parts. Hence for all
    UM_KERN_<LEVEL> definitions, only the SOH character is retained in the actual
    definition, while the remainder ends up in the comment. E.g. in
    include/generated/asm-offsets.h we get
    
        #define UM_KERN_INFO "\001" /* "6" KERN_INFO */
    
    instead of
    
        #define UM_KERN_INFO "\001" "6" /* KERN_INFO */
    
    This causes spurious '^A' output in some kernel messages:
    
        Calibrating delay loop... 4640.76 BogoMIPS (lpj=23203840)
        pid_max: default: 32768 minimum: 301
        Mount-cache hash table entries: 256
        ^AChecking that host ptys support output SIGIO...Yes
        ^AChecking that host ptys support SIGIO on close...No, enabling workaround
        ^AUsing 2.6 host AIO
        NET: Registered protocol family 16
        bio: create slab <bio-0> at 0
        Switching to clocksource itimer
    
    To fix this:
      - Move the mapping from UM_KERN_<LEVEL> to KERN_<LEVEL> from
        arch/um/include/shared/common-offsets.h to
        arch/um/include/shared/user.h, which is preincluded for all userspace
        parts,
      - Preinclude include/linux/kern_levels.h for all userspace parts, to
        obtain the in-kernel KERN_<LEVEL> constant definitions. This doesn't
        violate the kernel/userspace separation, as include/linux/kern_levels.h
        is self-contained and doesn't expose any other kernel internals.
      - Remove the now unused STR() and DEFINE_STR() macros.
    Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
    Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
    9429ec96
user.h 1.45 KB