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authorYinghai Lu <Yinghai.Lu@Sun.COM>2008-01-30 13:33:09 +0100
committerIngo Molnar <mingo@elte.hu>2008-01-30 13:33:09 +0100
commitaaf230424204864e2833dcc1da23e2cb0b9f39cd (patch)
treea42042f5135aa63a780964bd053ae174211ab62f /Documentation
parenta261670aed2b5b77a20ce9b15fed57abeb126c0e (diff)
downloadlinaro-lsk-aaf230424204864e2833dcc1da23e2cb0b9f39cd.tar.gz
x86: disable the GART early, 64-bit
For K8 system: 4G RAM with memory hole remapping enabled, or more than 4G RAM installed. when try to use kexec second kernel, and the first doesn't include gart_shutdown. the second kernel could have different aper position than the first kernel. and second kernel could use that hole as RAM that is still used by GART set by the first kernel. esp. when try to kexec 2.6.24 with sparse mem enable from previous kernel (from RHEL 5 or SLES 10). the new kernel will use aper by GART (set by first kernel) for vmemmap. and after new kernel setting one new GART. the position will be real RAM. the _mapcount set is lost. Bad page state in process 'swapper' page:ffffe2000e600020 flags:0x0000000000000000 mapping:0000000000000000 mapcount:1 count:0 Trying to fix it up, but a reboot is needed Backtrace: Pid: 0, comm: swapper Not tainted 2.6.24-rc7-smp-gcdf71a10-dirty #13 Call Trace: [<ffffffff8026401f>] bad_page+0x63/0x8d [<ffffffff80264169>] __free_pages_ok+0x7c/0x2a5 [<ffffffff80ba75d1>] free_all_bootmem_core+0xd0/0x198 [<ffffffff80ba3a42>] numa_free_all_bootmem+0x3b/0x76 [<ffffffff80ba3461>] mem_init+0x3b/0x152 [<ffffffff80b959d3>] start_kernel+0x236/0x2c2 [<ffffffff80b9511a>] _sinittext+0x11a/0x121 and [ffffe2000e600000-ffffe2000e7fffff] PMD ->ffff81001c200000 on node 0 phys addr is : 0x1c200000 RHEL 5.1 kernel -53 said: PCI-DMA: aperture base @ 1c000000 size 65536 KB new kernel said: Mapping aperture over 65536 KB of RAM @ 3c000000 So could try to disable that GART if possible. According to Ingo > hm, i'm wondering, instead of modifying the GART, why dont we simply > _detect_ whatever GART settings we have inherited, and propagate that > into our e820 maps? I.e. if there's inconsistency, then punch that out > from the memory maps and just dont use that memory. > > that way it would not matter whether the GART settings came from a [old > or crashing] Linux kernel that has not called gart_iommu_shutdown(), or > whether it's a BIOS that has set up an aperture hole inconsistent with > the memory map it passed. (or the memory map we _think_ i tried to pass > us) > > it would also be more robust to only read and do a memory map quirk > based on that, than actively trying to change the GART so early in the > bootup. Later on we have to re-enable the GART _anyway_ and have to > punch a hole for it. > > and as a bonus, we would have shored up our defenses against crappy > BIOSes as well. add e820 modification for gart inconsistent setting. gart_fix_e820=off could be used to disable e820 fix. Signed-off-by: Yinghai Lu <yinghai.lu@sun.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/kernel-parameters.txt4
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 40db7dd1d92..860a9087549 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -660,6 +660,10 @@ and is between 256 and 4096 characters. It is defined in the file
gamma= [HW,DRM]
+ gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
+ Format: off | on
+ default: on
+
gdth= [HW,SCSI]
See header of drivers/scsi/gdth.c.