>>> On 8/16/2012 at 05:11 PM, David Boyes <dbo...@sinenomine.net> wrote: 
> Does it still need a EW segment, or is it now well behaved for shared R/O? 

I guess it does.  From /usr/src/linux/arch/s390/kernel/early.c:
        hlen = snprintf(defsys_cmd, DEFSYS_CMD_SIZE,
                        "DEFSYS %s 00000-%.5X EW %.5X-%.5X SR %.5X-%.5X",
                        kernel_nss_name, stext_pfn - 1, stext_pfn,
                        eshared_pfn - 1, eshared_pfn, end_pfn);

#ifdef CONFIG_BLK_DEV_INITRD
        if (INITRD_START && INITRD_SIZE) {
                sinitrd_pfn = PFN_DOWN(__pa(INITRD_START));
                einitrd_pfn = PFN_UP(__pa(INITRD_START + INITRD_SIZE));
                min_size = einitrd_pfn << 2;
                hlen += snprintf(defsys_cmd + hlen, DEFSYS_CMD_SIZE - hlen,
                                 " EW %.5X-%.5X", sinitrd_pfn, einitrd_pfn);
        }
#endif

        snprintf(defsys_cmd + hlen, DEFSYS_CMD_SIZE - hlen,
                 " EW MINSIZE=%.7iK PARMREGS=0-13", min_size);
        defsys_cmd[DEFSYS_CMD_SIZE - 1] = '\0';
        snprintf(savesys_cmd, SAVESYS_CMD_SIZE, "SAVESYS %s \n IPL %s",
                 kernel_nss_name, kernel_nss_name);
        savesys_cmd[SAVESYS_CMD_SIZE - 1] = '\0';

        __cpcmd(defsys_cmd, NULL, 0, &response);


I can't say I understand why EW is being used.  Perhaps one of the guys in IBM 
development can comment on that.


Mark Post

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