diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/lguest/boot.c | 48 | ||||
| -rw-r--r-- | arch/x86/lguest/i386_head.S | 8 |
2 files changed, 30 insertions, 26 deletions
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index a0179fc..a55b090 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -99,7 +99,7 @@ static cycle_t clock_base; * When lazy_mode is set, it means we're allowed to defer all hypercalls and do * them as a batch when lazy_mode is eventually turned off. Because hypercalls * are reasonably expensive, batching them up makes sense. For example, a - * large mmap might update dozens of page table entries: that code calls + * large munmap might update dozens of page table entries: that code calls * paravirt_enter_lazy_mmu(), does the dozen updates, then calls * lguest_leave_lazy_mode(). * @@ -164,8 +164,8 @@ void async_hcall(unsigned long call, /*:*/ /*G:033 - * Here are our first native-instruction replacements: four functions for - * interrupt control. + * After that diversion we return to our first native-instruction + * replacements: four functions for interrupt control. * * The simplest way of implementing these would be to have "turn interrupts * off" and "turn interrupts on" hypercalls. Unfortunately, this is too slow: @@ -184,7 +184,7 @@ static unsigned long save_fl(void) return lguest_data.irq_enabled; } -/* "restore_flags" just sets the flags back to the value given. */ +/* restore_flags() just sets the flags back to the value given. */ static void restore_fl(unsigned long flags) { lguest_data.irq_enabled = flags; @@ -357,7 +357,7 @@ static void lguest_cpuid(unsigned int *eax, unsigned int *ebx, * it. The Host needs to know when the Guest wants to change them, so we have * a whole series of functions like read_cr0() and write_cr0(). * - * We start with CR0. CR0 allows you to turn on and off all kinds of basic + * We start with cr0. cr0 allows you to turn on and off all kinds of basic * features, but Linux only really cares about one: the horrifically-named Task * Switched (TS) bit at bit 3 (ie. 8) * @@ -390,7 +390,7 @@ static void lguest_clts(void) current_cr0 &= ~X86_CR0_TS; } -/* CR2 is the virtual address of the last page fault, which the Guest only ever +/* cr2 is the virtual address of the last page fault, which the Guest only ever * reads. The Host kindly writes this into our "struct lguest_data", so we * just read it out of there. */ static unsigned long lguest_read_cr2(void) @@ -398,7 +398,7 @@ static unsigned long lguest_read_cr2(void) return lguest_data.cr2; } -/* CR3 is the current toplevel pagetable page: the principle is the same as +/* cr3 is the current toplevel pagetable page: the principle is the same as * cr0. Keep a local copy, and tell the Host when it changes. */ static void lguest_write_cr3(unsigned long cr3) { @@ -411,7 +411,7 @@ static unsigned long lguest_read_cr3(void) return current_cr3; } -/* CR4 is used to enable and disable PGE, but we don't care. */ +/* cr4 is used to enable and disable PGE, but we don't care. */ static unsigned long lguest_read_cr4(void) { return 0; @@ -432,7 +432,7 @@ static void lguest_write_cr4(unsigned long val) * maps virtual addresses to physical addresses using "page tables". We could * use one huge index of 1 million entries: each address is 4 bytes, so that's * 1024 pages just to hold the page tables. But since most virtual addresses - * are unused, we use a two level index which saves space. The CR3 register + * are unused, we use a two level index which saves space. The cr3 register * contains the physical address of the top level "page directory" page, which * contains physical addresses of up to 1024 second-level pages. Each of these * second level pages contains up to 1024 physical addresses of actual pages, @@ -440,7 +440,7 @@ static void lguest_write_cr4(unsigned long val) * * Here's a diagram, where arrows indicate physical addresses: * - * CR3 ---> +---------+ + * cr3 ---> +---------+ * | --------->+---------+ * | | | PADDR1 | * Top-level | | PADDR2 | @@ -498,8 +498,7 @@ static void lguest_set_pmd(pmd_t *pmdp, pmd_t pmdval) * * ... except in early boot when the kernel sets up the initial pagetables, * which makes booting astonishingly slow. So we don't even tell the Host - * anything changed until we've done the first page table switch. - */ + * anything changed until we've done the first page table switch. */ static void lguest_set_pte(pte_t *ptep, pte_t pteval) { *ptep = pteval; @@ -720,10 +719,10 @@ static void lguest_time_init(void) /* Set up the timer interrupt (0) to go to our simple timer routine */ set_irq_handler(0, lguest_time_irq); - /* Our clock structure look like arch/i386/kernel/tsc.c if we can use - * the TSC, otherwise it's a dumb nanosecond-resolution clock. Either - * way, the "rating" is initialized so high that it's always chosen - * over any other clocksource. */ + /* Our clock structure looks like arch/x86/kernel/tsc_32.c if we can + * use the TSC, otherwise it's a dumb nanosecond-resolution clock. + * Either way, the "rating" is set so high that it's always chosen over + * any other clocksource. */ if (lguest_data.tsc_khz) lguest_clock.mult = clocksource_khz2mult(lguest_data.tsc_khz, lguest_clock.shift); @@ -749,7 +748,7 @@ static void lguest_time_init(void) * to work. They're pretty simple. */ -/* The Guest needs to tell the host what stack it expects traps to use. For +/* The Guest needs to tell the Host what stack it expects traps to use. For * native hardware, this is part of the Task State Segment mentioned above in * lguest_load_tr_desc(), but to help hypervisors there's this special call. * @@ -850,13 +849,16 @@ static __init char *lguest_memory_setup(void) return "LGUEST"; } -/* Before virtqueues are set up, we use LHCALL_NOTIFY on normal memory to - * produce console output. */ +/* We will eventually use the virtio console device to produce console output, + * but before that is set up we use LHCALL_NOTIFY on normal memory to produce + * console output. */ static __init int early_put_chars(u32 vtermno, const char *buf, int count) { char scratch[17]; unsigned int len = count; + /* We use a nul-terminated string, so we have to make a copy. Icky, + * huh? */ if (len > sizeof(scratch) - 1) len = sizeof(scratch) - 1; scratch[len] = '\0'; @@ -883,7 +885,7 @@ static __init int early_put_chars(u32 vtermno, const char *buf, int count) * Our current solution is to allow the paravirt back end to optionally patch * over the indirect calls to replace them with something more efficient. We * patch the four most commonly called functions: disable interrupts, enable - * interrupts, restore interrupts and save interrupts. We usually have 10 + * interrupts, restore interrupts and save interrupts. We usually have 6 or 10 * bytes to patch into: the Guest versions of these operations are small enough * that we can fit comfortably. * @@ -1015,7 +1017,7 @@ __init void lguest_init(void) asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory"); /* The Host uses the top of the Guest's virtual address space for the - * Host<->Guest Switcher, and it tells us how much it needs in + * Host<->Guest Switcher, and it tells us how big that is in * lguest_data.reserve_mem, set up on the LGUEST_INIT hypercall. */ reserve_top_address(lguest_data.reserve_mem); @@ -1065,6 +1067,6 @@ __init void lguest_init(void) /* * This marks the end of stage II of our journey, The Guest. * - * It is now time for us to explore the nooks and crannies of the three Guest - * devices and complete our understanding of the Guest in "make Drivers". + * It is now time for us to explore the layer of virtual drivers and complete + * our understanding of the Guest in "make Drivers". */ diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S index ebc6ac7..95b6fbc 100644 --- a/arch/x86/lguest/i386_head.S +++ b/arch/x86/lguest/i386_head.S @@ -6,7 +6,7 @@ #include <asm/processor-flags.h> /*G:020 This is where we begin: head.S notes that the boot header's platform - * type field is "1" (lguest), so calls us here. The boot header is in %esi. + * type field is "1" (lguest), so calls us here. * * WARNING: be very careful here! We're running at addresses equal to physical * addesses (around 0), not above PAGE_OFFSET as most code expectes @@ -17,13 +17,15 @@ * boot. */ .section .init.text, "ax", @progbits ENTRY(lguest_entry) - /* Make initial hypercall now, so we can set up the pagetables. */ + /* We make the "initialization" hypercall now to tell the Host about + * us, and also find out where it put our page tables. */ movl $LHCALL_LGUEST_INIT, %eax movl $lguest_data - __PAGE_OFFSET, %edx int $LGUEST_TRAP_ENTRY /* The Host put the toplevel pagetable in lguest_data.pgdir. The movsl - * instruction uses %esi implicitly. */ + * instruction uses %esi implicitly as the source for the copy we' + * about to do. */ movl lguest_data - __PAGE_OFFSET + LGUEST_DATA_pgdir, %esi /* Copy first 32 entries of page directory to __PAGE_OFFSET entries. |
