• Michael Holzheu's avatar
    [PATCH] s390: debug feature changes · 66a464db
    Michael Holzheu authored
    This patch changes the memory allocation method for the s390 debug feature.
    Trace buffers had been allocated using the get_free_pages() function before.
    Therefore it was not possible to get big memory areas in a running system due
    to memory fragmentation.  Now the trace buffers are subdivided into several
    subbuffers with pagesize.  Therefore it is now possible to allocate more
    memory for the trace buffers and more trace records can be written.
    
    In addition to that, dynamic specification of the size of the trace buffers is
    implemented.  It is now possible to change the size of a trace buffer using a
    new debugfs file instance.  When writing a number into this file, the trace
    buffer size is changed to 'number * pagesize'.
    
    In the past all the traces could be obtained from userspace by accessing files
    in the "proc" filesystem.  Now with debugfs we have a new filesystem which
    should be used for debugging purposes.  This patch moves the debug feature
    from procfs to debugfs.
    
    Since the interface of debug_register() changed, all device drivers, which use
    the debug feature had to be adjusted.
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    66a464db
tape_core.c 30.9 KB