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[patch #4818] Dynamic memory allocation for Linux Device drivers in glue

From: Gianluca Guida
Subject: [patch #4818] Dynamic memory allocation for Linux Device drivers in glue.
Date: Sat, 21 Jan 2006 19:39:55 +0000
User-agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.8) Gecko/20051111 Firefox/1.5


                 Summary: Dynamic memory allocation for Linux Device drivers
in glue.
                 Project: The GNU Hurd
            Submitted by: gianluca
            Submitted on: Sat 01/21/06 at 19:39
                Category: GNU Mach
                Priority: 6
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open



This patches rewrite GNU Mach's physical page allocation routines and make
glued linux drivers use these new routines instead of limited, specific and
redundant routines existing in the  actual linux glue.

vm/vm_resident.c now can handle (thanks to information given from the
architecture-dependant component) two specific zones of physical memory: DMA
capable and non-DMA capable.
In the x86 we suffer a limit from the ISA bus, that can just let its DMA chip
access first 16Mb of memory. Thus, when ISA drivers need memory for DMA
operation, we must be sure to supply pages below that limit.

GNU Mach didn't had support for special zones in the page, perhaps because
when people were hacking it 16Mb seemed to be a far limit in x86 systems.
Actual Linux glue solved the problem by allocating a fixed, unfreeable amount
of ram below 16Mb at bootstrap and limiting the whole linux subsection to use
that memory only, which in fact was stolen from the system. Furthermore, and
this is very frequent in Mach, it added yet another fixed and arbitrary limit
for memory usage to generic components.

What this patch basically does is to add multizone allocation  (DMA and
non-DMA) to GNUMach and hack the glue to make it uses this new feature, thus
making allocation from linux drivers dynamical. As a result, linux glue code
is simpler. As a side effect, some unused, obsolete native device drivers in
Mach (i386/i386at ones) get broken, since they use a slow routine to allocate
DMA memory that now has been removed.

This work is still unfinished (the pageout daemon has to free unused
collected memory from kmalloc/kfree, but that's an easy task). I posted this
patch for testing only. I actually had installed and normally used a Debian
GNU/Hurd system with this patch, but I would be happy if people would test

Thanks for reading this,

2006-01-20  Gianluca Guida  <glguida@gmail.com>

        * vm/pmap.h (pmap_is_dma, pmap_is_normal): New functions.

        * vm/page.h (VM_PAGE_DMA): New macro.
        (vm_page_queue_free): Variable removed.
        (vm_page_queue_free_dma, vm_page_queue_free_normal): New
        (vm_page_physaddr_lookup, vm_page_grab_flags)
        (vm_page_grab_contiguous_pages_flags): New functions.
        (first_phys_addr, last_phys_addr): Declarations removed.
        (phys_first_addr, phys_last_addr): New declarations.

        * vm/vm_resident.c (vm_page_free_bitmap)
        (vm_page_free_bitmap_bitsz): New variables.
        (vm_page_free_bitmap_set, vm_page_free_bitmap_unset)
        (vm_page_free_bitmap_alloc, vm_page_array_init, vm_page_array_add)
        (vm_page_physaddr_lookup): New functions.
        (vm_page_bootstrap): Initialize vm_page_queue_free_normal and
        vm_page_queue_free_dma. Call vm_page_free_bitmap_alloc.
        (pmap_startup): Call vm_page_array_init. Add page to vm_page_array
        for physaddress-to-vm_page_t resolution. Do not release page in
        any particular order.
        (vm_page_create): Add page to vm_page_array.
        (vm_page_grab_flags, vm_page_grab_contiguous_pages_queue)
        (vm_page_grab_contiguous_flags): New functions.
        (vm_page_grab, vm_page_grab_contiguous_pages): Function rewritten.
        (vm_page_release): Select proper free list based on page type (DMA
        or non-DMA). Use Mach's queue handling funcitons not .next and
        .prev pointers manually. Set vm_page_free_bitmap when freeing a

        * i386/i386at/model_dep.c (use_all_mem): Always set to 1.
        (init_alloc_aligned): Do not use any particular oder during
        bootstrap allocation.
        (alloc_dma_mem): Function removed.

        * kern/startup.c: Include <vm/pmap.h>.
        (setup_main): Calculate memory size using phys_last_addr and

        * i386/intel/pmap.c (vm_page_normal_first, vm_page_normal_last)
        (vm_page_dma_first, vm_page_dma_last): New variables.
        (pmap_bootstrap): Set proper values to vm_page_normal_* and
        vm_page_dma_* based on system's memory.
        (pmap_is_dma, pmap_is_normal): New functions.

        * kern/startup.c: Removed /* XXX */ comments, since phys_last_addr
        and phys_first_addr are exported by pmap.c now.
        * linux/dev/glue/kmem.c: Include <mach/error.h>
        (MEM_CHUNK_SIZE, MEM_CHUNKS, NBPW): Macro removed.
        (pages_free, memlist, num_page_collect, linux_mem_avail):
        Variables removed.
        (memlist_dma, memlist_nml): New variables.
        (linux_kmem_init): No initialization needed anymore (all code
        (coalesce_blocks): Coalesce separately DMA memory blocks and
        non-DMA memory blocks.
        (linux_kmalloc): Check for DMA in priority argument. Select proper
        memlist to get blocks from. Pass dma information to
        (linux_kfree): Select proper memlist to free memory into.
        (collect_kmalloc_pages): Function removed.
        (collect_kmalloc_pages_dma, collect_kmalloc_pages_nml): New
        (__get_free_pages, free_pages): Functions rewritten.

        * linux/dev/init/main.c (CONTIG_ALLOC, NBPW): Macro removed.
        (CONTIG_ALLOC_ORDER): New macro.
        (linux_init): Use __getfreepages to allocate PCI initialization
        memory and free_pages to free it.
        (alloc_contig_mem, free_contig_mem): Functions removed.


File Attachments:

Date: Sat 01/21/06 at 19:39  Name: vm_resident-zoned-patch.diff  Size:
44.15KB   By: gianluca
vm_resident zoned patch 1


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