Messages in this thread Patch in this message | | | From | Michael Frank <> | Subject | [PATCH] 2.4.25-rc1: Add user friendliness to highmem= option | Date | Sat, 7 Feb 2004 19:50:53 +0800 |
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Marcelo,
Enclosed is a patch for x86 to make highmem= option easier to use.
- Automates alignment of highmem zone - Fixes invalid highmem settings whether too small or to large - Adds entry in kernel-parameters.txt
Highmem emulation can be used on any machine with at least 68MB RAM.
The patch does not add to bloat as it part of __init code.
Please consider applying it as it makes this option quite usable
Regards Michael
Examples on a machine with 495MB available RAM:
highmem=1m
Warning highmem=1MB is too small and has been adjusted to: 4MB. Warning bad highmem zone alignment 0x1f0000, highmem size will be adjusted. Warning lowmem size adjusted for zone alignment to: 492MB. Warning highmem size adjusted for zone alignment to: 3MB. 3MB HIGHMEM available. 492MB LOWMEM available.
highmem=300m
Warning bad highmem zone alignment 0x1f0000, highmem size will be adjusted. Warning lowmem size adjusted for zone alignment to: 196MB. Warning highmem size adjusted for zone alignment to: 299MB. 299MB HIGHMEM available. 196MB LOWMEM available.
highmem=450m
Warning highmem size adjusted for a minimum of 64MB lowmem to: 431MB. 431MB HIGHMEM available. 64MB LOWMEM available.
highmem=5000m
Warning highmem=5000MB is bigger than available 495MB and will be adjusted. Warning highmem size adjusted for a minimum of 64MB lowmem to: 431MB. 431MB HIGHMEM available. 64MB LOWMEM available.
mem=70m highmem=300m
user-defined physical RAM map: user: 0000000000000000 - 000000000009fc00 (usable) user: 000000000009fc00 - 00000000000a0000 (reserved) user: 00000000000f0000 - 0000000000100000 (reserved) user: 0000000000100000 - 0000000004600000 (usable) Warning highmem=300MB is bigger than available 70MB and will be adjusted. Warning highmem size adjusted for a minimum of 64MB lowmem to: 6MB. 6MB HIGHMEM available. 64MB LOWMEM available.
mem=66m highmem=1m
user-defined physical RAM map: user: 0000000000000000 - 000000000009fc00 (usable) user: 000000000009fc00 - 00000000000a0000 (reserved) user: 00000000000f0000 - 0000000000100000 (reserved) user: 0000000000100000 - 0000000004200000 (usable) Error highmem support requires at least 68MB but only 66MB are available. 0MB HIGHMEM available. 66MB LOWMEM available.
mem=68m highmem=10m
user-defined physical RAM map: user: 0000000000000000 - 000000000009fc00 (usable) user: 000000000009fc00 - 00000000000a0000 (reserved) user: 00000000000f0000 - 0000000000100000 (reserved) user: 0000000000100000 - 0000000004400000 (usable) Warning highmem size adjusted for a minimum of 64MB lowmem to: 4MB. 4MB HIGHMEM available. 64MB LOWMEM available.
diff -uN -r -X /home/mhf/sys/dont/dontdiff linux-2.4.25-rc1-Vanilla/arch/i386/kernel/setup.c linux-2.4.25-rc1-mhf176/arch/i386/kernel/setup.c --- linux-2.4.25-rc1-Vanilla/arch/i386/kernel/setup.c 2004-02-07 02:52:37.000000000 +0800 +++ linux-2.4.25-rc1-mhf176/arch/i386/kernel/setup.c 2004-02-07 18:53:47.000000000 +0800 @@ -861,9 +861,12 @@ disable_ioapic_setup(); #endif /* - * highmem=size forces highmem to be exactly 'size' bytes. + * highmem=size forces highmem to be at most 'size' bytes. * This works even on boxes that have no highmem otherwise. * This also works to reduce highmem size on bigger boxes. + * + * Note: highmem sise is adjusted downward for proper zone + * alignment of the highmem physical start address. */ else if (!memcmp(from, "highmem=", 8)) highmem_pages = memparse(from+8, &from) >> PAGE_SHIFT; @@ -918,25 +921,31 @@ /* * Determine low and high memory ranges: */ + +#define ZONE_REQUIRED_PAGE_ALIGNMENT (1UL << (MAX_ORDER-1)) +#define ZONE_REQUIRED_PAGE_ALIGNMENT_MASK (ZONE_REQUIRED_PAGE_ALIGNMENT-1) +#define PAGES_FOR_64MB (64*1024*1024/PAGE_SIZE) + static unsigned long __init find_max_low_pfn(void) { unsigned long max_low_pfn; max_low_pfn = max_pfn; + if (max_low_pfn > MAXMEM_PFN) { if (highmem_pages == -1) highmem_pages = max_pfn - MAXMEM_PFN; if (highmem_pages + MAXMEM_PFN < max_pfn) max_pfn = MAXMEM_PFN + highmem_pages; if (highmem_pages + MAXMEM_PFN > max_pfn) { - printk("only %luMB highmem pages available, ignoring highmem size of %uMB.\n", pages_to_mb(max_pfn - MAXMEM_PFN), pages_to_mb(highmem_pages)); - highmem_pages = 0; + printk("Warning reducing highmem=%luMB to: %luMB.\n", + pages_to_mb(highmem_pages), pages_to_mb(max_pfn - MAXMEM_PFN)); + highmem_pages = max_pfn - MAXMEM_PFN; } max_low_pfn = MAXMEM_PFN; #ifndef CONFIG_HIGHMEM /* Maximum memory usable is what is directly addressable */ - printk(KERN_WARNING "Warning only %ldMB will be used.\n", - MAXMEM>>20); + printk(KERN_WARNING "Warning only %ldMB will be used.\n",MAXMEM>>20); if (max_pfn > MAX_NONPAE_PFN) printk(KERN_WARNING "Use a PAE enabled kernel.\n"); else @@ -950,27 +959,53 @@ } #endif /* !CONFIG_X86_PAE */ #endif /* !CONFIG_HIGHMEM */ - } else { - if (highmem_pages == -1) - highmem_pages = 0; + } else if (highmem_pages == -1) + highmem_pages = 0; #if CONFIG_HIGHMEM - if (highmem_pages >= max_pfn) { - printk(KERN_ERR "highmem size specified (%uMB) is bigger than pages available (%luMB)!.\n", pages_to_mb(highmem_pages), pages_to_mb(max_pfn)); - highmem_pages = 0; - } - if (highmem_pages) { - if (max_low_pfn-highmem_pages < 64*1024*1024/PAGE_SIZE){ - printk(KERN_ERR "highmem size %uMB results in smaller than 64MB lowmem, ignoring it.\n", pages_to_mb(highmem_pages)); - highmem_pages = 0; - } - max_low_pfn -= highmem_pages; - } + if (!highmem_pages) + goto out; + if (max_pfn < PAGES_FOR_64MB + ZONE_REQUIRED_PAGE_ALIGNMENT * 2) { + printk(KERN_ERR + "Error highmem support requires at least %uMB but only %uMB are available.\n", + pages_to_mb(PAGES_FOR_64MB + ZONE_REQUIRED_PAGE_ALIGNMENT * 2),pages_to_mb(max_pfn)); + highmem_pages = 0; + goto out; + } + if (highmem_pages > max_pfn) { + printk(KERN_WARNING + "Warning highmem=%uMB is bigger than available %luMB and will be adjusted.\n", + pages_to_mb(highmem_pages), pages_to_mb(max_pfn)); + } + if (highmem_pages <= ZONE_REQUIRED_PAGE_ALIGNMENT) { + printk(KERN_WARNING + "Warning highmem=%uMB is too small and has been adjusted to: %uMB.\n", + pages_to_mb(highmem_pages),pages_to_mb(ZONE_REQUIRED_PAGE_ALIGNMENT * 2)); + highmem_pages = ZONE_REQUIRED_PAGE_ALIGNMENT * 2; + } + if (max_low_pfn < highmem_pages || max_low_pfn-highmem_pages < PAGES_FOR_64MB){ + highmem_pages = max_low_pfn - PAGES_FOR_64MB; + printk(KERN_WARNING + "Warning highmem size adjusted for a minimum of 64MB lowmem to: %uMB.\n", + pages_to_mb(highmem_pages)); + } + max_low_pfn -= highmem_pages; + if (max_low_pfn & ZONE_REQUIRED_PAGE_ALIGNMENT_MASK) { + printk("Warning bad highmem zone alignment 0x%lx, highmem size will be adjusted.\n",(max_low_pfn & ZONE_REQUIRED_PAGE_ALIGNMENT_MASK) << PAGE_SHIFT); + highmem_pages -= ZONE_REQUIRED_PAGE_ALIGNMENT - (max_low_pfn & ZONE_REQUIRED_PAGE_ALIGNMENT_MASK); + max_low_pfn &= ~ZONE_REQUIRED_PAGE_ALIGNMENT_MASK; + max_low_pfn += ZONE_REQUIRED_PAGE_ALIGNMENT; + printk(KERN_WARNING + "Warning lowmem size adjusted for zone alignment to: %uMB.\n", + pages_to_mb(max_low_pfn)); + printk(KERN_WARNING + "Warning highmem size adjusted for zone alignment to: %uMB.\n", + pages_to_mb(highmem_pages)); + } #else - if (highmem_pages) - printk(KERN_ERR "ignoring highmem size on non-highmem kernel!\n"); + if (highmem_pages) + printk(KERN_ERR "Error highmem size on non-highmem kernel ignored\n"); #endif - } - +out: return max_low_pfn; } diff -uN -r -X /home/mhf/sys/dont/dontdiff linux-2.4.25-rc1-Vanilla/Documentation/kernel-parameters.txt linux-2.4.25-rc1-mhf176/Documentation/kernel-parameters.txt --- linux-2.4.25-rc1-Vanilla/Documentation/kernel-parameters.txt 2004-02-06 17:06:14.000000000 +0800 +++ linux-2.4.25-rc1-mhf176/Documentation/kernel-parameters.txt 2004-02-07 19:10:39.000000000 +0800 @@ -241,6 +241,12 @@ hfmodem= [HW,AX25] + highmem=size[KMG] [IA32,KNL,BOOT] forces highmem to be at most 'size' bytes. + This works even on boxes with at least 68MB RAM that have no highmem + otherwise. This also works to reduce highmem size on bigger boxes. + Note: highmem is adjusted downward for proper zone alignment of the + highmem physical start address + hisax= [HW,ISDN] i810= [HW,DRM] - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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