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    SubjectRe: [RFC][PATCH -mm] Make swsusp work on i386 with PAE
    Hi!

    > The purpose of the appended patch is to make swsusp work on i386 with PAE,
    > but it should also allow i386 systems without PSE to use swsusp.
    >
    > The patch creates temporary page tables located in resume-safe page frames
    > during the resume and uses them for restoring the suspend image (the same
    > approach is used on x86-64).
    >
    > It has been tested on an i386 system with PAE and survived several
    > suspend-resume cycles in a row, but I have no systems without PSE, so that
    > requires some testing.

    Thanks, looks okay to me. I guess Andi Kleen would be right person to
    review it in detail?

    Lack of assembly modifications is good.

    I guess this should be now removed? (include/asm-i386/suspend.h)

    arch_prepare_suspend(void)
    {
    /* If you want to make non-PSE machine work, turn off paging
    in swsusp_arch_suspend. swsusp_pg_dir should have identity mapping, so
    it could work... */
    if (!cpu_has_pse) {
    printk(KERN_ERR "PSE is required for swsusp.\n");
    return -EPERM;
    }

    > +/*
    > + * Create a middle page table on a resume-safe page and put a pointer to it in
    > + * the given global directory entry. This only returns the gd entry
    > + * in non-PAE compilation mode, since the middle layer is folded.
    > + */
    > +static pmd_t *resume_one_md_table_init(pgd_t *pgd)
    > +{
    > + pud_t *pud;
    > + pmd_t *pmd_table;
    > +
    > +#ifdef CONFIG_X86_PAE
    > + pmd_table = (pmd_t *)get_safe_page(GFP_ATOMIC);
    > + if (!pmd_table)
    > + return pmd_table;

    I'd do plain old return NULL; here.

    > + /* Map with big pages if possible, otherwise create
    > + * normal page tables.
    > + * NOTE: We can mark everything as executable here
    > + */
    > + if (cpu_has_pse) {
    > + set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
    > + pfn += PTRS_PER_PTE;

    Perhaps disabling PSE here can help getting some testing?

    Okay, I guess I should really test this one... Seems good enough for
    -mm to me, but it should preferably stay there for a _long_ time.
    Pavel
    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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