From: Stas Sergeev The previous discussion was started here: http://www.uwsg.iu.edu/hypermail/linux/kernel/0211.0/0477.html but in 2.4 times this was kind of problematic. Now, with the lazy bitmap allocation and per-CPU TSS, this will really not drain any resources I think. 8K TSS increase and 8K per process *that does ioperm()* - I think it is not very bad. The reasons why I need that, are described in the URL above. Basically this will allow to use full-screen VESA under dosemu (without LFB though), and this may be also helpfull for the XFree project and some other projects: http://www.uwsg.iu.edu/hypermail/linux/kernel/9807.1/1079.html Signed-off-by: Andrew Morton --- 25-akpm/include/asm-i386/desc.h | 3 ++- 25-akpm/include/asm-i386/processor.h | 6 +++--- 25-akpm/include/asm-mips/processor.h | 4 ++-- 25-akpm/include/asm-x86_64/processor.h | 4 ++-- 4 files changed, 9 insertions(+), 8 deletions(-) diff -puN include/asm-i386/desc.h~larger-io-bitmap include/asm-i386/desc.h --- 25/include/asm-i386/desc.h~larger-io-bitmap Fri Jun 18 15:40:31 2004 +++ 25-akpm/include/asm-i386/desc.h Fri Jun 18 15:40:31 2004 @@ -44,7 +44,8 @@ __asm__ __volatile__ ("movw %w3,0(%2)\n\ static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, void *addr) { - _set_tssldt_desc(&cpu_gdt_table[cpu][entry], (int)addr, 235, 0x89); + _set_tssldt_desc(&cpu_gdt_table[cpu][entry], (int)addr, + offsetof(struct tss_struct, __cacheline_filler) - 1, 0x89); } #define set_tss_desc(cpu,addr) __set_tss_desc(cpu, GDT_ENTRY_TSS, addr) diff -puN include/asm-i386/processor.h~larger-io-bitmap include/asm-i386/processor.h --- 25/include/asm-i386/processor.h~larger-io-bitmap Fri Jun 18 15:40:31 2004 +++ 25-akpm/include/asm-i386/processor.h Fri Jun 18 15:40:31 2004 @@ -297,9 +297,9 @@ extern unsigned int mca_pentium_flag; #define TASK_UNMAPPED_BASE (PAGE_ALIGN(TASK_SIZE / 3)) /* - * Size of io_bitmap, covering ports 0 to 0x3ff. + * Size of io_bitmap. */ -#define IO_BITMAP_BITS 1024 +#define IO_BITMAP_BITS 65536 #define IO_BITMAP_BYTES (IO_BITMAP_BITS/8) #define IO_BITMAP_LONGS (IO_BITMAP_BYTES/sizeof(long)) #define IO_BITMAP_OFFSET offsetof(struct tss_struct,io_bitmap) @@ -391,7 +391,7 @@ struct tss_struct { /* * pads the TSS to be cacheline-aligned (size is 0x100) */ - unsigned long __cacheline_filler[5]; + unsigned long __cacheline_filler[37]; /* * .. and then another 0x100 bytes for emergency kernel stack */ diff -puN include/asm-mips/processor.h~larger-io-bitmap include/asm-mips/processor.h --- 25/include/asm-mips/processor.h~larger-io-bitmap Fri Jun 18 15:40:31 2004 +++ 25-akpm/include/asm-mips/processor.h Fri Jun 18 15:40:31 2004 @@ -137,9 +137,9 @@ extern unsigned int vced_count, vcei_cou #endif /* - * Size of io_bitmap in longwords: 32 is ports 0-0x3ff. + * Size of io_bitmap in longwords. */ -#define IO_BITMAP_SIZE 32 +#define IO_BITMAP_SIZE 2048 #define NUM_FPU_REGS 32 diff -puN include/asm-x86_64/processor.h~larger-io-bitmap include/asm-x86_64/processor.h --- 25/include/asm-x86_64/processor.h~larger-io-bitmap Fri Jun 18 15:40:31 2004 +++ 25-akpm/include/asm-x86_64/processor.h Fri Jun 18 15:40:31 2004 @@ -178,9 +178,9 @@ static inline void clear_in_cr4 (unsigne (test_thread_flag(TIF_IA32) ? TASK_UNMAPPED_32 : TASK_UNMAPPED_64) /* - * Size of io_bitmap, covering ports 0 to 0x3ff. + * Size of io_bitmap. */ -#define IO_BITMAP_BITS 1024 +#define IO_BITMAP_BITS 65536 #define IO_BITMAP_BYTES (IO_BITMAP_BITS/8) #define IO_BITMAP_LONGS (IO_BITMAP_BYTES/sizeof(long)) #define IO_BITMAP_OFFSET offsetof(struct tss_struct,io_bitmap) _